Abstract:

A fluorine-containing compound represented by a general formula (c-1)
shown below:
RX-AN-(OR2)a [Chemical Formula 1]
(c-1)
[wherein, RX represents an organic group, AN represents a
naphthalene ring that may have a substituent, R2 represents a base
dissociable group, and a represents 1 or 2, provided that at least one
among AN and said a R2 groups contains a fluorine atom].

Claims:

1. A fluorine-containing compound represented by a general formula (c-1)
shown below:[Chemical Formula 1]RX-AN-(OR2)a
(c-1)[wherein, RX represents an organic group, AN represents a
naphthalene ring that may have a substituent, R2 represents a base
dissociable group, and a represents 1 or 2, provided that at least one
among AN and said a R2 groups contains a fluorine atom].

2. A fluorine-containing compound according to claim 1, wherein said
R2 represents one or more groups selected from among groups
represented by general formulas (II-1) to (II-3) shown below:
##STR00080## [wherein, each R3 independently represents a
hydrocarbon group that may contain a fluorine atom].

3. A fluorine-containing compound according to claim 1, represented by a
general formula (c0-1) shown below: ##STR00081## [wherein, R1
represents a hydrogen atom, a lower alkyl group or a halogenated lower
alkyl group, and AN, R2 and a are as defined above].

4. A fluorine-containing compound according to claim 3, represented by a
general formula (c0-11) shown below: ##STR00082## [wherein, R1 is as
defined above, R4 represents a base dissociable group containing a
fluorine atom, R5 and R6 each independently represents a
substituent, c is an integer of 0 to 3, d is an integer of 0 to 3, and e
is 1 or 2, provided that d+e is an integer of 1 to 4].

5. A fluorine-containing compound according to claim 1, which is a
polymeric compound having a structural unit represented by a general
formula (c1-1) shown below: ##STR00083## [wherein, R1 represents a
hydrogen atom, a lower alkyl group or a halogenated lower alkyl group,
and AN, R2 and a are as defined above].

6. A fluorine-containing compound according to claim 5, which is a
polymeric compound having a structural unit represented by a general
formula (c1-11) shown below: ##STR00084## [wherein, R1 is as defined
above, R4 represents a base dissociable group containing a fluorine
atom, R5 and R6 each independently represents a substituent, c
is an integer of 0 to 3, d is an integer of 0 to 3, and e is 1 or 2,
provided that d+e is an integer of 1 to 4].

7. A resist composition for immersion exposure, comprising a base
component (A) that exhibits changed solubility in an alkali developing
solution under action of acid, an acid generator component that generates
acid upon exposure, and a fluorine-containing compound (C) represented by
a general formula (c-1) shown below:[Chemical Formula
7]RX-AN-(OR2)a (c-1)[wherein, RX represents an
organic group, AN represents a naphthalene ring that may have a
substituent, R2 represents a base dissociable group, and a
represents 1 or 2, provided that at least one among AN and said a
R2 groups includes a fluorine atom].

8. A resist composition for immersion exposure according to claim 7,
wherein said R2 represents one or more groups selected from among
groups represented by general formulas (II-1) to (II-3) shown below:
##STR00085## [wherein, each R3 independently represents a
hydrocarbon group that may contain a fluorine atom].

9. A resist composition for immersion exposure according to claim 7 or 8,
wherein said fluorine-containing compound (C) is a compound represented
by a general formula (c0-1) shown below: ##STR00086## [wherein, R1
represents a hydrogen atom, a lower alkyl group or a halogenated lower
alkyl group, and AN, R2 and a are as defined above].

10. A resist composition for immersion exposure according to claim 9,
wherein said fluorine-containing compound (C) is a compound represented
by a general formula (c0-11) shown below: ##STR00087## [wherein, R1
is as defined above, R4 represents a base dissociable group
containing a fluorine atom, R5 and R6 each independently
represents a substituent, c is an integer of 0 to 3; d is an integer of 0
to 3; and e is 1 or 2 provided that d+e is an integer of 1 to 4].

11. A resist composition for immersion exposure according to claim 7,
wherein said fluorine-containing compound (C) is a polymeric compound
having a structural unit represented by a general formula (c1-1) shown
below: ##STR00088## [wherein, R1 represents a hydrogen atom, a lower
alkyl group or a halogenated lower alkyl group, and AN, R2 and
a are as defined above].

12. A resist composition for immersion exposure according to claim 11,
wherein said fluorine-containing compound (C) is a polymeric compound
having a structural unit represented by a general formula (c1-11) shown
below: ##STR00089## [wherein, R1 is as defined above, R4
represents a base dissociable group containing a fluorine atom, R5
and R6 each independently represents a substituent, c is an integer
of 0 to 3; d is an integer of 0 to 3; and e is 1 or 2 provided that d+e
is an integer of 1 to 4].

13. A resist composition for immersion exposure according to claim 7,
wherein said base component (A) is a base component that exhibits
increased solubility in an alkali developing solution under action of
acid.

14. A resist composition for immersion exposure according to claim 13,
wherein said base component (A) comprises a resin component (A1) that
exhibits increased solubility in an alkali developing solution under
action of acid, and said resin component (A1) comprises a structural unit
(a1) derived from an acrylate ester containing an acid dissociable,
dissolution inhibiting group.

15. A resist composition for immersion exposure according to claim 14,
wherein said resin component (A1) further comprises a structural unit
(a2) derived from an acrylate ester containing a lactone-containing
cyclic group.

17. The resist composition for immersion exposure according to claim 7,
further comprising a nitrogen-containing organic compound (D).

18. A method of forming a resist pattern, comprising: forming a resist
film on a substrate using a resist composition for immersion exposure
according to claim 7, subjecting said resist film to immersion exposure,
and subjecting said resist film to alkali developing to form a resist
pattern.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention relates to a fluorine-containing compound, a
resist composition for immersion exposure (liquid immersion lithography)
containing the fluorine-containing compound, and a method of forming a
resist pattern that uses the resist composition for immersion exposure,

[0003]Priority is claimed on Japanese Patent Application No. 2007-311701,
filed Nov. 30, 2007, the content of which is incorporated herein by
reference.

[0004]2. Description of Related Art

[0005]In lithography techniques, for example, a resist film composed of a
resist material is formed on a substrate, and the resist film is
subjected to selective exposure of radial rays such as light or electron
beam through a mask having a predetermined pattern, followed by
development, thereby forming a resist pattern having a predetermined
shape on the resist film.

[0006]For miniaturization of semiconductor devices, shortening of the
wavelength of the exposure light source, and increasing of the numerical
aperture (NA) of the projector lens have progressed. Currently, exposure
apparatuses in which an ArF excimer laser having a wavelength of 193 nm
is used as an exposure light source and NA=0.84 have been developed. As
shortening of the wavelength of the exposure light source progresses, it
is required to improve various lithography properties of the resist
material, such as the sensitivity to the exposure light source and the
resolution capable of reproducing patterns of minute dimensions. As a
resist material which satisfies these conditions, a chemically amplified
resist is used, which includes a base resin that exhibits changed
solubility in an alkali developing solution under the action of acid and
an acid generator that generates acid upon exposure.

[0007]Currently, resins that contain structural units derived from
(meth)acrylate esters within the main chain (acrylic resins) are
typically used as base resins for resists that use ArF excimer laser
lithography, as they exhibit excellent transparency in the vicinity of
193 nm.

[0008]Here, the term "(meth)acrylic acid" is a generic term that includes
either or both of acrylic acid having a hydrogen atom bonded to the
α-position and methacrylic acid having a methyl group bonded to the
α-position. The term "(meth)acrylate ester" is a generic term that
includes either or both of the acrylate ester having a hydrogen atom
bonded to the α-position and the methacrylate ester having a methyl
group bonded to the α-position. The term "(meth)acrylate" is a
generic term that includes either or both of the acrylate having a
hydrogen atom bonded to the α-position and the methacrylate having
a methyl group bonded to the α-position.

[0009]As a technique for further improving the resolution, a lithography
method called liquid immersion lithography (hereafter, frequently
referred to as "immersion exposure") is known in which exposure
(immersion exposure) is conducted in a state where the region between the
objective lens of the exposure apparatus and the sample is filled with a
solvent (an immersion medium) that has a larger refractive index than the
refractive index of air (see, for example, Non-Patent Document 1).

[0010]According to this type of immersion exposure, it is considered that
higher resolutions equivalent to those obtained using a shorter
wavelength light source or a larger NA lens can be obtained using the
same exposure light source wavelength, with no lowering of the depth of
focus. Furthermore, immersion exposure can be conducted using a
conventional exposure apparatus. As a result, it is expected that
immersion exposure will enable the formation of resist patterns of higher
resolution and superior depth of focus at lower costs. Accordingly, in
the production of semiconductor devices, which requires enormous capital
investment, immersion exposure is attracting considerable attention as a
method that offers significant potential to the semiconductor industry,
both in terms of cost and in terms of lithography properties such as
resolution.

[0011]Immersion lithography is effective in forming patterns having
various shapes. Further, immersion exposure is expected to be capable of
being used in combination with currently studied super-resolution
techniques, such as phase shift methods and modified illumination
methods. Currently, as the immersion exposure technique, techniques using
an ArF excimer laser as an exposure source are being actively studied,
and water is mainly used as the immersion medium.

[0012]In recent years, fluorine-containing compounds have been attracting
attention for their properties such as water repellency and transparency,
and active research and development of fluorine-containing compounds have
been conducted in various fields. For example, in the fields of resist
materials, currently, an acid-labile group such as a methoxymethyl group,
tert-butyl group or tert-butyloxycarbonyl group is being introduced into
a fluorine-containing polymeric compound, and the fluorine-containing
polymeric compound is then used as a base resin for a chemically
amplified positive resist. However, when such a fluorine-containing
polymeric compound is used as a base resin for a chemically amplified
positive resist, disadvantages arise in that a large quantity of out-gas
is generated following exposure, and the resistance to dry etching gases
(namely, the etching resistance) is unsatisfactory.

[0013]Recently, as a fluorine-containing polymeric compound exhibiting
excellent etching resistance, a fluorine-containing polymeric compound
having an acid-labile group containing a cyclic hydrocarbon group has
been reported (see, for example, Non-Patent Document 2).

[0014][Non-Patent Document 1]

[0015]Proceedings of SPIE (U.S.), vol. 5754, pp. 119-128 (2005)

[0016][Non-Patent Document 2]

[0017]Proceedings of SPIE (U.S.), vol. 4690, pp. 76-83 (2002)

SUMMARY OF THE INVENTION

[0018]In immersion exposure, it is required to use a resist material that
exhibits not only general lithography properties (such as sensitivity,
resolution, and etching resistance), but also properties suited to
immersion lithography. For example, in immersion exposure, when the
resist film comes into contact with the immersion medium, elution of
substances contained in the resist into the immersion medium (substance
elution) occurs. This substance elution causes phenomena such as
degeneration of the resist film and change in the refractive index of the
immersion medium, thereby adversely affecting the lithography properties.
The amount of this substance elution is affected by the properties of the
resist film surface (such as the hydrophilicity or hydrophobicity). For
example, by enhancing the hydrophobicity of the resist film surface, this
substance elution can be reduced. Further, when the immersion medium is
water, and immersion exposure is performed using a scanning-type
immersion exposure apparatus as disclosed in Non-Patent Document 1, a
water tracking ability wherein the immersion medium is capable of
tracking the movement of the lens is required. When the water tracking
ability is poor, the exposure speed decreases, and as a result, there is
a possibility that the productivity may be adversely affected. It is
presumed that the water tracking ability can be improved by enhancing the
hydrophobicity of the resist film (rendering the resist film
hydrophobic).

[0019]Accordingly, it is presumed that the above-described characteristic
problems of immersion lithography, which require a reduction in substance
elution and an improvement in the water tracking ability, can be
addressed by enhancing the hydrophobicity of the resist film surface.
However, if the resist film is simply rendered hydrophobic, then adverse
effects are seen on the lithography properties. For example, as the
hydrophobicity of the resist film is increased, defects tend to occur
more readily on the resist film following alkali developing. Particularly
in the case of a positive resist composition, defects tend to occur more
readily in the unexposed portions of the resist. The term "defects"
describes general abnormalities within a resist film that are detected
when observed from directly above the alkali developed resist film using
a surface defect detection apparatus (product name: "KLA") manufactured
by KLA-TENCOR Corporation. Examples of these "abnormalities" include
post-developing scum, foam, dust, bridges (structures that bridge
different portions of the resist pattern), color irregularities, foreign
deposits, and residues.

[0020]It is considered that a material which is hydrophobic during
immersion exposure but then becomes hydrophilic during developing can
address the problems described above. However, materials exhibiting such
properties are essentially unknown.

[0021]The present invention takes the above circumstances into
consideration, with an object of providing a novel fluorine-containing
compound that is useful as an additive for a resist composition for
immersion exposure, a resist composition for immersion composure that
includes the fluorine-containing compound, and a method of forming a
resist pattern that uses the resist composition for immersion composure.

[0022]In order to achieve the above object, the present invention adopts
the aspects described below,

[0023]Namely, a first aspect of the present invention is a
fluorine-containing compound represented by general formula (c-1) shown
below:

RX-AN-(OR2)a [Chemical Formula 1]

(c-1)

[0024][wherein, RX represents an organic group, AN represents a
naphthalene ring that may have a substituent, R2 represents a base
dissociable group, and a represents 1 or 2, provided that at least one
among AN and the a R2 groups includes a fluorine atom].

[0025]A second aspect of the present invention is a resist composition for
immersion exposure including a base component (A) that exhibits changed
solubility in an alkali developing solution under the action of acid, an
acid generator component that generates acid upon exposure, and a
fluorine-containing compound (C) represented by general formula (c-1)
shown below:

RX-AN-(OR2)a [Chemical Formula 2]

(c-1)

[0026][wherein, RX represents an organic group, AN represents a
naphthalene ring that may have a substituent, R2 represents a base
dissociable group, and a represents 1 or 2, provided that at least one
among AN and the a R2 groups includes a fluorine atom].

[0027]A third aspect of the present invention is a method of forming a
resist pattern, including; forming a resist film on a substrate using a
resist composition for immersion exposure according to the second aspect
described above, subjecting the resist film to immersion exposure, and
subjecting the resist film to alkali developing to form a resist pattern.

[0028]In the present description and claims, "exposure" is not limited to
irradiation with light, and is used as a general concept that includes
irradiation with any form of radiation, including an ArF excimer laser,
KrF excimer laser, F2 excimer laser, as well as EUV (Extreme Ultra
Violet), VUV (Vacuum Ultra Violet), EB (Electron Beam), X-ray and soft
X-ray radiation.

[0030]A "structural unit" refers to a monomer unit that contributes to the
formation of a polymeric compound (namely, a polymer or copolymer).

[0031]According to the present invention, there are provided a novel
fluorine-containing compound that is useful as an additive for a resist
composition for immersion exposure, a resist composition for immersion
composure that includes the fluorine-containing compound, and a method of
forming a resist pattern that uses the resist composition for immersion
composure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a diagram describing an advancing angle (θ1), a
receding angle (θ2) and a sliding angle (θ3).

[0034]A fluorine-containing compound of the present invention (hereafter
frequently referred to as "fluorine-containing compound (C)") is
represented by general formula (c-1) shown above.

[0035]In formula (c-1), a represents 1 or 2, and is preferably 1.

[0036]R2 represents a base dissociable group.

[0037]In the present description and claims, the term "base dissociable
group" describes a group that dissociates under the action of an alkali
developing solution, thereby improving the solubility of the compound in
the alkali developing solution (and preferably describes a group that
dissociates under the action of a 2.38% by weight aqueous solution of
TMAH at 23° C.). In other words, the fluorine-containing compound
(C) of the present invention is a compound that is substantially
insoluble in alkali developing solutions, but exhibits increased
solubility in alkali developing solutions under the action of the alkali
developing solution. Specifically, by including a base dissociable group,
the fluorine-containing compound (C) is substantially insoluble in alkali
developing solutions, but when the base dissociable group dissociates
under the action of an alkali developing solution, a hydrophilic phenolic
hydroxyl group (namely, an OH group bonded to AN) is generated,
thereby increasing the solubility of the compound in the alkali
developing solution.

[0038]There are no particular limitations on the base dissociable group
provided it satisfies the above definition. However, the structure of the
fluorine-containing compound (C) must include at least one fluorine atom
among AN and the a R2 groups. Accordingly, in those cases where
the AN group within the fluorine-containing compound (C) includes no
fluorine atoms, at least one R2 group is a base dissociable group
having a fluorine atom. In those cases where the AN group within the
fluorine-containing compound (C) includes a fluorine atom, the R2
group may or may not contain a fluorine atom.

[0039]As specific examples of the base dissociable group, one or more
groups selected from among groups represented by general formulas (II-1)
to (II-3) shown below are preferred, and in terms of exhibiting superior
effects for the present invention and ease of synthesis, groups
represented by general formula (II-1) are particularly preferred.

##STR00001##

[wherein, each R3 independently represents a hydrocarbon group that
may contain a fluorine atom.]

[0040]In formula (II-1), R3 represents a hydrocarbon group that may
contain a fluorine atom.

[0041]The hydrocarbon group represented by R3 may be an unsubstituted
hydrocarbon group composed solely of carbon and hydrogen atoms, or a
fluorine-substituted hydrocarbon group in which some or all of the
hydrogen atoms of the unsubstituted hydrocarbon group have been
substituted with fluorine atoms.

[0042]The hydrocarbon group is preferably an aliphatic hydrocarbon group,
but may be an aromatic hydrocarbon group.

[0043]In the present description and claims, the term "aliphatic" is a
relative concept used in relation to the term "aromatic", and defines a
group or compound or the like that has no aromaticity.

[0044]An aliphatic hydrocarbon group is a hydrocarbon group that has no
aromaticity. The aliphatic hydrocarbon group may be either saturated or
unsaturated, but is preferably saturated. In other words, the aliphatic
hydrocarbon group is preferably an unsubstituted alkyl group or a
fluorine-substituted alkyl group.

[0045]The unsubstituted alkyl group may be a linear, branched or cyclic
group, or may be a combination of a linear or branched alkyl group and a
cyclic alkyl group.

[wherein, R7 to R9 each independently represents a linear alkyl
group of 1 to 5 carbon atoms.]

[0048]Each alkyl group represented by R7 to R9 is preferably an
ethyl group or methyl group, and is most preferably a methyl group,

[0049]The unsubstituted cyclic alkyl group preferably contains 4 to 15
carbon atoms, and examples thereof include groups in which one hydrogen
atom has been removed from a monocycloalkane, or a polycycloalkane such
as a bicycloalkane, tricycloalkane or tetracycloalkane. Specific examples
include monocycloalkyl groups such as a cyclopentyl group and cyclohexyl
group, and polycycloalkyl groups such as an adamantyl group, norbornyl
group, isobornyl group, tricyclodecanyl group and tetracyclododecanyl
group.

[0050]Examples of the combination of an unsubstituted linear or branched
alkyl group and a cyclic alkyl group include groups in which a cyclic
alkyl group is bonded to a linear or branched alkyl group as a
substituent, and groups in which a linear or branched alkyl group is
bonded to a cyclic alkyl group as a substituent.

[0051]Examples of the fluorine-substituted alkyl group include groups in
which some or all of the hydrogen atoms within an unsubstituted alkyl
group described above have been substituted with fluorine atoms.

[0052]The fluorine-substituted alkyl group may be either a group in which
some of the hydrogen atoms of the unsubstituted alkyl group have been
substituted with fluorine atoms, or a group in which all of the hydrogen
atoms of the unsubstituted alkyl group have been substituted with
fluorine atoms (namely, a perfluoroalkyl group).

[0053]As the fluorinated alkyl group for R3, a linear or branched
fluorine-substituted alkyl group is preferred, and a group represented by
a formula --R41-R42 [wherein, R41 represents an
unsubstituted alkylene group of 1 to 9 carbon atoms, and R42
represents a fluorine-substituted alkyl group of 1 to 9 carbon atoms,
provided that the combined number of carbon atoms within R41 and
R42 is not more than 10] is particularly preferred.

[0054]In the above formula, R41 is preferably a linear or branched
alkylene group of 1 to 5 carbon atoms, and is more preferably a methylene
group, ethylene group or propylene group.

[0055]R42 is preferably a linear or branched fluorine-substituted
alkyl group of 1 to 5 carbon atoms, and a perfluoroalkyl group is
particularly desirable. Of such groups, a trifluoromethyl group or
tetrafluoroethyl group is particularly preferred,

[0056]In formula (c-1), AN represents a naphthalene ring that may
have a substituent.

[0057]In the group AN, examples of the substituent that may be bonded
to the naphthalene ring include a halogen atom, alkyl group, alkoxy
group, halogenated lower alkyl group or oxygen atom (═O). Examples of
the halogen atom include a fluorine atom, chlorine atom, iodine atom or
bromine atom.

[0058]In the present invention, the naphthalene ring preferably either has
no substituents, or has at least one fluorine atom as a substituent.

[0059]As described above, in the structure of the fluorine-containing
compound (C), at least one among AN and the a R2 groups must
include a fluorine atom. Accordingly, in those cases where R2
contains a fluorine atom, AN may or may not contain a fluorine atom.
Furthermore, in those cases where R2 contains no fluorine atoms,
AN includes a fluorine atom.

[0060]In those cases where the naphthalene ring contains at least one
fluorine atom as a substituent, the fluorination ratio for the
naphthalene ring, namely the ratio (%) of the number of fluorine atoms
relative to the combined number of hydrogen atoms and fluorine atoms
contained within the naphthalene ring, is preferably within a range from
10 to 100%, more preferably from 50 to 100%, and is most preferably 100%.
In other words, those groups where all of the hydrogen atoms within the
naphthalene ring have been substituted with fluorine atoms are the most
desirable.

[0061]In formula (c-1), the bonding position of RX on the naphthalene
ring of AN is not particularly limited, although position 1 or
position 2 on the naphthalene ring is preferred, and position 2 is the
most desirable. Further, the bonding position of --OR2 is also not
particularly limited, although positions 5 to 8 on the naphthalene ring
are preferred, and position 5 or position 6 is more preferred.

[0062]In formula (c-1), RX may be either a high molecular weight
organic group composed of a plurality of structural units, or a low
molecular weight organic group. In other words, the fluorine-containing
compound (C) of the present invention may be either a polymeric compound
(a polymer or copolymer), or a low molecular weight compound (a
non-polymer).

[0063]In the following description, in those cases where the
fluorine-containing compound (C) is a low molecular weight compound, the
fluorine-containing compound (C) is frequently referred to as the
"fluorine-containing compound (CO)". Further, in those cases where the
fluorine-containing compound (C) is a polymeric compound, the
fluorine-containing compound (C) is frequently referred to as the
"fluorine-containing compound (C1)".

[0064][Fluorine-Containing Compound (CO)]

[0065]In the fluorine-containing compound (CO), as the group RX, a
substituent containing a polymerizable group is preferred.

[0066]The polymerizable group is a group that makes the compound
containing the polymerizable group able to undergo polymerization such as
radical polymerization. As the polymerizable group, the types of
polymerizable groups generally used in monomers can be used. Examples of
the polymerizable group include groups containing an ethylenic
unsaturated double bond.

[0067]Specific examples of groups containing an ethylenic unsaturated
double bond include groups represented by
CH2═C(R03)--(CH2)b-- and groups represented by
CH2═C(R03)--C(═O)--O--. Of these, groups represented by
CH2═C(R03)--(CH2)b-- and groups represented by
CH2═C(R03)--C(═O)--O-- are preferred.

[0070]Specific examples of the halogenated lower alkyl group for R03
include groups in which some or all of the hydrogen atoms in an
aforementioned lower alkyl group have been substituted with halogen
atoms. Examples of the halogen atom include a fluorine atom, chlorine
atom, bromine atom and iodine atom, and a fluorine atom is particularly
preferred,

[0071]R03 is preferably a hydrogen atom, a lower alkyl group or a
fluorinated lower alkyl group, and is more preferably a hydrogen atom or
a methyl group.

[0072]b represents an integer of 0 to 2, is preferably 0 or 1, and is most
preferably 0.

[0073]The substituent containing a polymerizable group may be a group
composed solely of the polymerizable group, or a group composed of the
polymerizable group and another group besides the polymerizable group.

[0074]Examples of groups composed of a polymerizable group and another
group besides the polymerizable group include groups formed from an
above-mentioned polymerizable group and a divalent linking group.
Examples of the divalent linking group include hydrocarbon groups and
groups containing a hetero atom.

[0075]Examples of the hydrocarbon group include alkylene groups. This
alkylene group may be either linear or branched. The number of carbon
atoms within the alkylene group is preferably within a range from 1 to
12, more preferably from 1 to 5, and most preferably from 1 to 3.

[0076]Specific examples of the alkylene group include a methylene group
[--CH2--]; alkylmethylene groups such as --CH(CH3)--,
--CH(CH2CH3)--, --C(CH3)2--,
--C(CH3)(CH2CH3)--,
--C(CH3)(CH2CH2CH3)-- and
--C(CH2CH3)2--; an ethylene group [--CH2CH2--];
alkylethylene groups such as --CH(CH3)CH2--,
--CH(CH3)CH(CH3)--, --C(CH3)2CH2-- and
--CH(CH2CH3)CH2--; a trimethylene group (n-propylene
group) [--CH2CH2CH2--]; alkyltrimethylene groups such as
--CH(CH3)CH2CH2-- and --CH2CH(CH3)CH2--; a
tetramethylene group [--CH2CH2CH2CH2--];
alkyltetramethylene groups such as
--CH(CH3)CH2CH2CH2-- and
--CH2CH(CH3)CH2CH2--, and a pentamethylene group
[--CH2CH2CH2CH2CH2--].

[0077]A hetero atom refers to an atom other than a carbon atom or hydrogen
atom, and examples thereof include an oxygen atom, nitrogen atom, sulfur
atom or halogen atom.

[0078]Examples of groups containing a hetero atom include --O--,
--C(═O)--, --C(═O)--O--, --NH--, --NR04-- (wherein, R04
is an alkyl group), --NH--C(═O)--, ═N--, and groups composed of a
combination of one or more of these groups and a divalent hydrocarbon
group.

[0079]In the present invention, RX is preferably a group represented
by a general formula: CH2═C(R03)--(CH2)b-- or a
group represented by a general formula:
CH2═C(R03)--C(═O)--O--. In these formulas, R03 and
b are as defined above.

[0080]As the fluorine-containing compound (C0), compounds represented by
general formula (c0-1) shown below (hereafter referred to as "compound
(C0-1)"), and compounds represented by general formula (c0-2) shown below
(hereafter referred to as "compound (C0-2)") are preferred,

##STR00003##

[wherein, R1 represents a hydrogen atom, a lower alkyl group or a
halogenated lower alkyl group, and AN, R2 and a are as defined
above.]

[0081]Examples of R1 include the same groups as those exemplified
above for R03. R1is preferably a hydrogen atom, a lower alkyl
group or a fluorinated lower alkyl group, and is more preferably a
hydrogen atom or a methyl group.

[wherein, R1 is as defined above, R4 represents a base
dissociable group containing a fluorine atom, R5 and R6 each
independently represents a substituent, c is an integer of 0 to 3, d is
an integer of 0 to 3, and e is 1 or 2, provided that d+e is an integer of
1 to 4.]

[0084]Examples of R4 include those groups exemplified above for the
base dissociable group of R2 in general formula (c-1) that also
contain a fluorine atom.

[0085]Examples of the substituents for R5 and R6 include the
same groups as those exemplified above for the substituent that may be
bonded to the naphthalene ring in the group AN within general
formula (c-1), and of these, a fluorine atom is preferred.

[0086]In formulas (c0-11) and (c0-21), if due consideration is given to
factors such as ease of production, then compounds in which either both c
and d are 0, or c is 3, R5 is a fluorine atom, d is 4-e, and R6
is a fluorine atom are preferred.

[wherein, R1 is as defined above, and R3' represents a
hydrocarbon group containing a fluorine atom.]

[0089]Examples of R3' include those groups among the hydrocarbon
groups that may contain a fluorine atom exemplified above for R3 in
general formula (II-1) that do contain a fluorine atom.
Fluorine-substituted branched alkyl groups are particularly preferred,
and fluorine-substituted tertiary alkyl groups or groups represented by
the above-mentioned formula: --R41-R42 are even more desirable.
As the fluorine-substituted tertiary alkyl groups, groups represented by
general formula (c-2) above are the most desirable.

[0090]The fluorine-containing compound (C0) can be used favorably, without
modification, as an additive for a resist composition.

[0091]Further, in those cases where the fluorine-containing compound (C0)
is a compound that includes a polymerizable group, such as the
above-mentioned compounds (CO-1) and (CO-2), the fluorine-containing
compound (C0) may be converted to a polymeric compound, either by
homopolymerization or by copolymerization with one or more other
polymerizable compounds. In a similar manner to the fluorine-containing
compound (C0), this polymeric compound can be used favorably as an
additive for a resist composition for immersion exposure.

[0092]Of the compounds described above, the compound (C0-1) and the
compound (C0-2) are also useful for producing the fluorine-containing
compound (C1) described below.

[Fluorine-Containing Compound (C1)]

[0093]Examples of the fluorine-containing compound (C1) include polymeric
compounds having structural units derived from an aforementioned
fluorine-containing compound (C0) in which RX is a group containing
a polymerizable group.

[0094]Specific preferred examples include polymeric compounds having a
structural unit represented by general formula (c1-1) or (c1-2) shown
below (hereafter frequently referred to as a "structural unit (c1)").

[0097]In the fluorine-containing compound (C1), one type of structural
unit may be used as the structural unit (c1), or two or more types may be
used in combination.

[0098]The proportion of the structural unit (c1) within the
fluorine-containing compound (C1), relative to the combined total of all
the structural units that constitute the fluorine-containing compound
(C1), is preferably within a range from 10 to 100 mol %, more preferably
from 30 to 100 mol %, still more preferably from 50 to 100 mol %, and
still more preferably from 60 to 100 mol %. The proportion may be 100 mol
%,

[0099]The fluorine-containing compound (C1) may also include other
structural units besides the structural unit (c1), with the proviso that
the effects of the present invention are not impaired. There are no
particular limitations on these other structural units, although
structural units derived from compounds that are capable of
copolymerization with the compound that gives rise to the structural unit
(c1) (such as the above-mentioned compounds (C0-1) and (C0-2) or
precursors thereto) are preferred, Examples of these other structural
units include structural units (a1) to (a4), which are potential
structural units for a resin component (A1) of a resist composition for
immersion exposure described below, structural units derived from
hydroxystyrene, and structural units derived from styrene.

[0100]Examples of precursors to the compound (C0-1) and the compound
(C0-2) include compounds in which the --OR2 group within each
compound has been substituted with --OH (namely, naphthol compounds).

[0101]The weight average molecular weight (Mw) (the polystyrene equivalent
value determined by gel permeation chromatography) of the polymeric
compound (C1) is not particularly limited, but is preferably 2,000 to
50,000, more preferably 3,000 to 30,000, and most preferably 5,000 to
20,000. By making the weight average molecular weight less than the upper
limit of the above-mentioned range, the compound (C1) exhibits
satisfactory solubility in a resist solvent when used as a resist. On the
other hand, making the weight average molecular weight larger than the
lower limit of the above-mentioned range yields a more favorable dry
etching resistance and cross-sectional shape for the resist pattern.

[0102]Further, the dispersity (Mw/Mn) is preferably 1.0 to 5.0, more
preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. Here, Mn is the
number average molecular weight.

[0103]The polymeric compound (C1) can be used favorably as an additive for
a resist composition for immersion exposure,

<Method of Producing Fluorine-Containing Compound (C)>

[0104]The fluorine-containing compound (C) of the present invention can be
produced, for, example, by introducing a group represented by R2 at
the --OH group of a compound represented by RX-AN-(OH)a
(namely, by substituting the hydrogen atom of an --OH group with
R2).

[0105]This introduction of the group represented by R2 can be
conducted using conventional methods. Using the case where R2 is a
group represented by the above general formula (II-1) as an example, a
compound (C-1) in which the group R2 within general formula (c-1) is
a group represented by general formula (II-1) can be produced by reacting
a compound represented by general formula (I) shown below (hereafter
frequently referred to as "compound (I)"), and a compound (II)
represented by general formula (II) shown below.

##STR00009##

[wherein, RX, AN, a and R3 are as defined above, and
Xh represents a halogen atom or a hydroxyl group.]

[0106]Examples of the halogen atom represented by Xh include a
bromine atom, chlorine atom, iodine atom or fluorine atom. As Xh, a
bromine atom or chlorine atom is preferred as they offer superior
reactivity, and a chlorine atom is particularly desirable.

[0107]There are no particular limitations on the method used for reacting
the compound (I) and the compound (II), and for example, a method may be
used in which the compound (I) and the compound (II) are brought into
contact within a reaction solvent, in the presence of a base. In the case
where Xh represents a halogen atom, this method may be conducted by
adding the compound (II), in the presence of a base, to a solution
prepared by dissolving the compound (I) in a reaction solvent. Further,
in the case where Xh represents a hydroxyl group, the compound (I)
and the compound (II) can be reacted (via a condensation reaction) by
adding the compound (I), in the presence of a base and a condensation
agent, to a solution prepared by dissolving the compound (II) in a
reaction solvent. Further, when Xh represents a hydroxyl group, the
compound (I) and the compound (II) may also be reacted (via a
condensation reaction) by adding the compound (I), in the presence of an
acid, to a solution prepared by dissolving the compound (II) in a
reaction solvent.

[0108]As the compound (I) and the compound (II), either commercially
available products or synthesized compounds may be used.

[0109]The compound (I) may be either a low molecular weight compound such
as a vinylnaphthol, or a polymeric compound that includes a
hydroxynaphthol group on a side chain (such as a polyvinylnaphthol).

[0110]As the reaction solvent, any solvent that is capable of dissolving
the compound (I) and the compound (II) that act as the raw materials may
be used, and specific examples include tetrahydrofuran (THF), acetone,
dimethylformamide (DMF), dimethylacetamide, dimethylsulfoxide (DMSO) and
acetonitrile.

[0111]Examples of the base include organic bases such as triethylamine,
4-dimethylaminopyridine (DMAP) and pyridine, and inorganic bases such as
sodium hydride, K2CO3 and Cs2CO3.

[0112]As the acid, those acids typically used within
dehydration-condensation reactions can be used, and specific examples
include inorganic acids such as hydrochloric acid, sulfuric acid and
phosphoric acid, and organic acids such as methanesulfonic acid,
trifluoromethanesulfonic acid, benzenesulfonic acid and p-toluenesulfonic
acid, These acids may be used alone, or in combinations containing two or
more different acids.

[0113]Examples of the condensation agent include carbodiimide reagents
such as 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride
(EDCI), dicyclohexylcarboxyimide (DCC), diisopropylcarbodiimide and
carbodiimidazole, as well as tetraethyl pyrophosphate and
benzotriazole-N-hydroxytrisdimethylaminophosphonium hexafluorophosphate
(Bop reagent).

[0114]The amount added of the compound (II) relative to the compound (I)
is preferably within a range from 1 to 3 equivalents, and more preferably
from 1 to 2 equivalents.

[0115]The reaction temperature is preferably within a range from -20 to
40° C., and more preferably from 0 to 30° C.

[0116]The reaction time varies depending on factors such as the reactivity
of the compound (I) and compound (II) and the reaction temperature, but
is preferably within a range from 30 to 240 minutes, and more preferably
from 60 to 180 minutes.

[0117]Further, in those cases where the fluorine-containing compound (C)
is a polymeric compound, the compound can be obtained by conducting a
conventional radical polymerization or the like of the monomers that give
rise to the desired structural units (for example, the above-mentioned
compound (C0-1) and compound (C0-2)), using a radical polymerization
initiator such as azobisisobutyronitrile (AIBN).

[0118]The fluorine-containing compound (C) of the present invention
described above is a novel compound that has been unknown until now.

[0119]The fluorine-containing compound (C) can be used favorably as an
additive for a resist composition, and a resist composition containing
the added fluorine-containing compound (C) is useful as a resist
composition for immersion exposure.

[0120]There are no particular limitations on the resist composition
containing the added fluorine-containing compound (C), provided the
composition can be used for immersion exposure, although a chemically
amplified resist composition including a base component that exhibits
changed solubility in an alkali developing solution under the action of
acid, and an acid generator component that generates acid upon
irradiation is ideal.

[0121]The fluorine-containing compound (C) is ideal for use within the
resist composition for immersion exposure according to the present
invention described below.

<<Resist Composition for Immersion Exposure>>

[0122]The resist composition for immersion exposure according to the
present invention includes a base component (A) (hereafter, referred to
as "component (A)") that exhibits changed solubility in an alkali
developing solution under the action of acid, an acid generator component
(B) (hereafter, referred to as "component (B)") that generates acid upon
irradiation, and a fluorine-containing polymeric compound (C) (hereafter,
referred to as "component (C)") containing a group represented by general
formula (c-1) shown above and containing at least one fluorine atom.

<Component (A)>

[0123]As the component (A), either a single organic compound typically
used as a base component for a chemically amplified resist, or a mixture
of two or more such organic compounds, may be used.

[0124]The term "base component" refers to an organic compound capable of
forming a film, and preferably refers to an organic compound having a
molecular weight of 500 or more. When the organic compound has a
molecular weight of 500 or more, the film-forming ability is improved,
and a nano level resist pattern can be readily formed.

[0125]The organic compounds having a molecular weight of 500 or more that
may be used as the base component are broadly classified into low
molecular weight organic compounds having a molecular weight of 500 to
less than 2,000 (namely, "low molecular weight materials") and high
molecular weight organic compounds having a molecular weight of 2,000 or
more (namely, "polymeric materials"). Generally, a non-polymer is used as
the low molecular weight material, A resin a (polymer or copolymer) is
used as the polymeric material, and the "molecular weight" of the
polymeric material refers to the polystyrene equivalent weight average
molecular weight determined by GPC (gel permeation chromatography).
Hereafter, the simplified term "resin" refers to a resin having a
molecular weight of 2,000 or more.

[0126]The component (A) may be either a resin that exhibits changed alkali
solubility under the action of acid, or a low molecular weight material
that exhibits changed alkali solubility under the action of acid.

[0127]In those cases where the resist composition for immersion exposure
according to the present invention is a negative resist composition, a
base component that is soluble in an alkali developing solution is used
as the component (A), and a cross-linker is blended into the negative
resist composition.

[0128]In the negative resist composition, when acid is generated from the
component (B) upon exposure, the action of this acid causes cross-linking
between the base component and the cross-linker, and the cross-linked
portion becomes substantially insoluble in alkali. As a result, during
resist pattern formation, when a resist film obtained by applying the
negative resist composition to a substrate is selectively exposed, the
exposed portions of the resist become insoluble in an alkali developing
solution, whereas the unexposed portions remain soluble in the alkali
developing solution, meaning a resist pattern can be formed by alkali
developing.

[0129]As the component (A) of the negative resist composition, a resin
that is soluble in an alkali developing solution (hereafter frequently
referred to as an "alkali-soluble resin") is usually used.

[0130]As the alkali-soluble resin, it is preferable to use a resin having
structural units derived from at least one of an
α-(hydroxyalkyl)acrylic acid and a lower alkyl ester of an
α-(hydroxyalkyl)acrylic acid, as such resins enable the formation
of a satisfactory resist pattern with minimal swelling. Here, the term
"α-(hydroxyalkyl)acrylic acid" refers to one or both of acrylic
acid in which a hydrogen atom is bonded to the carbon atom on the
α-position having the carboxyl group bonded thereto, and
α-hydroxyalkylacrylic acid in which a hydroxyalkyl group
(preferably a hydroxyalkyl group of 1 to 5 carbon atoms) is bonded to the
carbon atom on the α-position.

[0131]As the cross-linker, typically, an ammo-based cross-linker such as a
glycoluril having a methylol group or alkoxymethyl group is preferable,
as it enables the formation of a resist pattern with minimal swelling.
The amount of the cross-linker added is preferably within a range from 1
to 50 parts by weight, relative to 100 parts by weight of the
alkali-soluble resin,

[0132]When the resist composition for immersion exposure according to the
present invention is a positive resist composition, as the component (A),
a base component that exhibits increased solubility in an alkali
developing solution under the action of acid is used. More specifically,
the component (A) is substantially insoluble in an alkali developing
solution prior to exposure, but when acid is generated from the component
(B) upon exposure, the action of this acid causes an increase in the
solubility of the base component in an alkali developing solution.
Accordingly, during resist pattern formation, when a resist film formed
by applying the positive resist composition to a substrate is selectively
exposed, the exposed portions change from being substantially insoluble
in an alkali developing solution to being alkali-soluble, whereas the
unexposed portions remain alkali-insoluble, meaning a resist pattern can
be formed by alkali developing.

[0133]In the resist composition of the present invention, the component
(A) is preferably a base component that exhibits increased solubility in
an alkali-developing solution under the action of acid. Namely, the
resist composition of the present invention is preferably a positive
resist composition.

[0134]The component (A) may be a resin component (A1) that exhibits
increased solubility in an alkali developing solution under the action of
acid (hereafter, frequently referred to as "component (A1)"), a low
molecular weight material (A2) that exhibits increased solubility in an
alkali developing solution under the action of acid (hereafter,
frequently referred to as "component (A2)"), or a mixture thereof.

[Component (A1)]

[0135]As the component (A1), either a single resin component (base resin)
typically used as a base component for a chemically amplified resist, or
a mixture of two or more such resin components, may be used.

[0136]In the present invention, as the component (A1), a resin containing
a structural unit derived from an acrylate ester is preferred.

[0137]In the present descriptions and the claims, the term "structural
unit derived from an acrylate ester" refers to a structural unit which is
formed by the cleavage of the ethylenic double bond of an acrylate ester.

[0138]The term "acrylate ester" is a generic term that includes acrylate
esters having a hydrogen atom bonded to the carbon atom on the
α-position, and acrylate esters having a substituent (an atom other
than a hydrogen atom or a group) bonded to the carbon atom on the
α-position. As the substituent, a lower alkyl group or a
halogenated lower alkyl group can be mentioned.

[0139]With respect to the "structural unit derived from an acrylate
ester", the "α-position (the carbon atom on the α-position)"
refers to the carbon atom having the carbonyl group bonded thereto,
unless specified otherwise.

[0140]In the acrylate ester, specific examples of the lower alkyl group
for the substituent at the α-position include linear or branched
lower alkyl groups such as a methyl group, ethyl group, propyl group,
isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl
group, isopentyl group and neopentyl group.

[0141]Further, specific examples of the halogenated lower alkyl group
include groups in which some or all of the hydrogen atoms of the
aforementioned "lower alkyl group for the substituent at the
α-position" are substituted with halogen atoms. Examples of the
halogen atom include a fluorine atom, chlorine atom, bromine atom and
iodine atom, and a fluorine atom is particularly desirable.

[0142]In the present invention, it is preferable that a hydrogen atom, a
lower alkyl group or a halogenated lower alkyl group, and more preferably
a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group,
is bonded to the α-position of the acrylate ester. In terms of
industrial availability, a hydrogen atom or a methyl group is the most
desirable.

[0144]Further, in addition to this structural unit (a1), the component
(A1) preferably also has a structural unit (a2) derived from an acrylate
ester that contains a lactone-containing cyclic group.

[0145]Moreover, in addition to the structural unit (a1), or in addition to
the combination of the structural units (a1) and (a2), the component (A1)
preferably also has a structural unit (a3) derived from an acrylate ester
that contains a polar group-containing aliphatic hydrocarbon group.

--Structural Unit (a1):

[0146]As the acid dissociable, dissolution inhibiting group within the
structural unit (a1), any of the groups that have been proposed as acid
dissociable, dissolution inhibiting groups for the base resins of
chemically amplified resists can be used, provided the group has an
alkali dissolution inhibiting effect that renders the entire component
(A1) insoluble in an alkali developing solution prior to dissociation,
and then following dissociation under action of acid, increases the
solubility of the entire component (A1) in the alkali developing
solution. Generally, groups that form either a cyclic or chain-like
tertiary alkyl ester with the carboxyl group of (meth)acrylic acid or the
like, and acetal-type acid dissociable, dissolution inhibiting groups
such as alkoxyalkyl groups are widely known.

[0147]Here, a "tertiary alkyl ester" describes a structure in which an
ester is formed by substituting the hydrogen atom of a carboxyl group
with a chain-like or cyclic tertiary alkyl group, and a tertiary carbon
atom within the chain-like or cyclic tertiary alkyl group is bonded to
the oxygen atom at the terminal of the carbonyloxy group (--C(O)--O--).
In this tertiary alkyl ester, the action of acid causes cleavage of the
bond between the oxygen atom and the tertiary carbon atom.

[0148]The chain-like or cyclic alkyl group may have a substituent.

[0149]Hereafter, for the sake of simplicity, groups that exhibit acid
dissociability as a result of the formation of a tertiary alkyl ester
with a carboxyl group are referred to as "tertiary alkyl ester-type acid
dissociable, dissolution inhibiting groups".

[0151]The term "aliphatic branched" refers to a branched structure having
no aromaticity. The "aliphatic branched acid dissociable, dissolution
inhibiting group" is not limited to structures constituted of only carbon
atoms and hydrogen atoms (not limited to hydrocarbon groups), but is
preferably a hydrocarbon group. Further, the "hydrocarbon group" may be
either saturated or unsaturated, but is preferably saturated.

[0153]The term "aliphatic cyclic group" refers to a monocyclic group or
polycyclic group that has no aromaticity. The number of carbon atoms
within the group is preferably from 5 to 30.

[0154]The "aliphatic cyclic group" within the structural unit (a1) may or
may not have a substituent. Examples of substituents include lower alkyl
groups of 1 to 5 carbon atoms, a fluorine atom, fluorinated lower alkyl
groups of 1 to 5 carbon atoms, and an oxygen atom (═O).

[0155]The basic ring of the "aliphatic cyclic group" exclusive of
substituents is not limited to structures constituted from only carbon
and hydrogen (not limited to hydrocarbon groups), but is preferably a
hydrocarbon group. Further, the "hydrocarbon group" may be either
saturated or unsaturated, but is preferably saturated. Furthermore, the
"aliphatic cyclic group" is preferably a polycyclic group.

[0156]As such aliphatic cyclic groups, groups in which one or more
hydrogen atoms have been removed from a monocycloalkane or a
polycycloalkane such as a bicycloalkane, tricycloalkane or
tetracycloalkane which may or may not be substituted with a lower alkyl
group, a fluorine atom or a fluorinated lower alkyl group, may be
exemplified. Specific examples include groups in which one or more
hydrogen atoms have been removed from a monocycloalkane such as
cyclopentane or cyclohexane, and groups in which one or more hydrogen
atoms have been removed from a polycycloalkane such as adamantane,
norbornane, isobornane, tricyclodecane or tetracyclododecane.

[0157]As the aliphatic cyclic group-containing acid dissociable,
dissolution inhibiting group, for example, a group which has a tertiary
carbon atom on the ring structure of the cycloalkyl group can be
mentioned. Specific examples include a 2-methyl-2-adamantyl group and a
2-ethyl-2-adamantyl group. Alternatively, groups having an aliphatic
cyclic group such as an adamantyl group, cyclohexyl group, cyclopentyl
group, norbornyl group, tricyclodecanyl group or tetracyclododecanyl
group, and a branched alkylene group having a tertiary carbon atom bonded
thereto, such as the groups bonded to the carbonyloxy group (--C(O)--O--)
in the structural units represented by general formulas (a1''-1) to
(a1''-6) shown below, may also be exemplified.

##STR00010##

[wherein, R represents a hydrogen atom, a lower alkyl group or a
halogenated lower alkyl group; and R15 and R16 each represents
an alkyl group (which may be linear or branched, and preferably has 1 to
5 carbon atoms).]

[0158]In general formulas (a1''-1) to (a1''-6) above, the lower alkyl
group or halogenated lower alkyl group for R are the same as the lower
alkyl group or halogenated lower alkyl group which may be bonded to the
α-position of the aforementioned acrylate ester.

[0159]An "acetal-type acid dissociable, dissolution inhibiting group"
generally substitutes a hydrogen atom at the terminal of an
alkali-soluble group such as a carboxyl group or hydroxyl group, so as to
be bonded with an oxygen atom. When acid is generated upon exposure, the
generated acid acts to break the bond between the acetal-type acid
dissociable, dissolution inhibiting group and the oxygen atom to which
the acetal-type, acid dissociable, dissolution inhibiting group is
bonded.

[wherein, R1' and R2' each independently represents a hydrogen
atom or a lower alkyl group, n represents an integer of 0 to 3, and Y
represents a lower alkyl group or an aliphatic cyclic group.]

[0161]In general formula (p1) above, n is preferably an integer of 0 to 2,
more preferably 0 or 1, and most preferably 0.

[0162]As the lower alkyl group for R1' and R2', the same groups
as the lower alkyl groups which may be bonded to the α-position of
the aforementioned acrylate ester may be exemplified, a methyl group or
ethyl group is preferable, and a methyl group is particularly desirable.

[0163]In the present invention, it is preferable that at least one of
R1' and R2' be a hydrogen atom. That is, it is preferable that
the acid dissociable, dissolution inhibiting group (p1) is a group
represented by general formula (p1-1) shown below.

##STR00012##

[wherein R1', n and Y are as defined above.]

[0164]As the lower alkyl group for Y, the same groups as the lower alkyl
groups which may be bonded to the α-position of the aforementioned
acrylate ester may be exemplified.

[0165]As the aliphatic cyclic group for Y, any of the aliphatic monocyclic
or polycyclic groups which have been proposed for conventional ArF
resists and the like can be appropriately selected for use. For example,
the same groups as those described above in connection with the
"aliphatic cyclic group" can be exemplified.

[0166]Further, as the acetal-type, acid dissociable, dissolution
inhibiting group, groups represented by general formula (p2) shown below
can also be exemplified.

##STR00013##

[wherein, R17 and R18 each independently represents a linear or
branched alkyl group or a hydrogen atom; and R19 represents a
linear, branched or cyclic alkyl group; or R17 and R19 each
independently represents a linear or branched alkylene group, wherein the
terminal of R17 is bonded to the terminal of R19 to form a
ring.]

[0167]The alkyl group for R17 and R18 preferably has 1 to 15
carbon atoms, and may be either linear or branched. As the alkyl group,
an ethyl group or a methyl group is preferable, and a methyl group is
most preferable.

[0168]It is particularly desirable that either one of R17 and
R18 be a hydrogen atom, and the other be a methyl group.

[0169]R19 represents a linear, branched or cyclic alkyl group which
preferably has 1 to 15 carbon atoms, and may be any of linear, branched
or cyclic.

[0170]When R19 represents a linear or branched alkyl group, it is
preferably an alkyl group of 1 to 5 carbon atoms, more preferably an
ethyl group or methyl group, and most preferably an ethyl group.

[0171]When R19 represents a cycloalkyl group, it preferably has 4 to
15 carbon atoms, more preferably 4 to 12 carbon atoms, and most
preferably 5 to 10 carbon atoms. As examples of the cycloalkyl group,
groups in which one or more hydrogen atoms have been removed from a
monocycloalkane or a polycycloalkane such as a bicycloalkane,
tricycloalkane or tetracycloalkane, which may or may not be substituted
with a fluorine atom or a fluorinated alkyl group, may be exemplified.
Specific examples include groups in which one or more hydrogen atoms have
been removed from a monocycloalkane such as cyclopentane or cyclohexane,
and groups in which one or more hydrogen atoms have been removed from a
polycycloalkane such as adamantane, norbornane, isobornane,
tricyclodecane or tetracyclododecane. Of these, a group in which one or
more hydrogen atoms have been removed from adamantane is preferable.

[0172]In general formula (p2) above, R17 and R19 may both
independently represent a linear or branched alkylene group (preferably
an alkylene group of 1 to 5 carbon atoms), and the terminal of R19
may be bonded to the terminal of R17.

[0173]In such a case, a cyclic group is formed by R17, R19, the
oxygen atom having R19 bonded thereto, and the carbon atom having
the oxygen atom and R17 bonded thereto. Such a cyclic group is
preferably a 4- to 7-membered ring, and more preferably a 4- to
6-membered ring. Specific examples of the cyclic group include a
tetrahydropyranyl group and tetrahydrofuranyl group.

[0174]As the structural unit (a1), it is preferable to use at least one
member selected from the group consisting of structural units represented
by general formula (a1-0-1) shown below and structural units represented
by general formula (a1-0-2) shown below.

[wherein, R represents a hydrogen atom, a lower alkyl group or a
halogenated lower alkyl group; X2 represents an acid dissociable,
dissolution inhibiting group; and Y2 represents an alkylene group or
an aliphatic cyclic group.]

[0175]In general formula (a1-0-1), the lower alkyl group and halogenated
lower alkyl group for R are the same as the lower alkyl group and
halogenated lower alkyl group which may be bonded to the α-position
of the aforementioned acrylate ester.

[0177]In general formula (a1-0-2), R is the same as the lower alkyl group
or halogenated lower alkyl group which may be bonded to the
α-position of the aforementioned acrylate ester,

[0178]X2 is the same as X1 in general formula (a1-0-1).

[0179]Y2 is preferably an alkylene group of 1 to 10 carbon atoms or a
divalent aliphatic cyclic group of 5 to 30 carbon atoms. As the aliphatic
cyclic group, the same groups as those exemplified above in connection
with the description of the "aliphatic cyclic group" can be used, with
the exception that two hydrogen atoms have been removed therefrom.

[0180]In those cases where Y2 is an alkylene group of 1 to 10 carbon
atoms, the number of carbon atoms within the group is more preferably 1
to 6, still more preferably 1 to 4, and is most preferably 1 to 3.

[0181]In those cases where Y2 is a divalent aliphatic cyclic group,
groups in which two or more hydrogen atoms have been removed from
cyclopentane, cyclohexane, norbornane, isobornane, adamantane,
tricyclodecane or tetracyclododecane are preferred.

[0182]Specific examples of the structural unit (a1) include structural
units represented by general formulas (a1-1) to (a1-4) shown below.

##STR00016##

[0183][wherein, X' represents a tertiary alkyl ester-type acid
dissociable, dissolution inhibiting group; Y represents a lower alkyl
group of 1 to 5 carbon atoms or an aliphatic cyclic group; n represents
an integer of 0 to 3; Y2 represents an alkylene group or an
aliphatic cyclic group; R is as defined above; and R1' and R2'
each independently represents a hydrogen atom or a lower alkyl group of 1
to 5 carbon atoms.]

[0184]In the above formulas, examples of X' include the same tertiary
alkyl ester-type acid dissociable, dissolution inhibiting groups as those
exemplified in connection with X1 in general formula (a1-0-1) shown
above.

[0185]Examples of R1', R2', n and Y include the same groups
exemplified above for R1', R2', n and Y in general formula (p1)
in connection with the description of the aforementioned "acetal-type
acid dissociable, dissolution inhibiting groups".

[0186]Examples of Y2 include the same groups as those exemplified for
Y2 in general formula (a1-0-2) shown above.

[0187]Specific examples of structural units represented by general formula
(a1-1) to (a1-4) are shown below.

[0188]Among the above units, structural units represented by general
formula (a1-1) are preferable. More specifically, at least one structural
unit selected from the group consisting of structural units represented
by formulas (a1-1-1) to (a1-1-6) and (a1-1-35) to (a1-1-41) is more
preferable.

[0189]Further, as the structural unit (a1), structural units represented
by general formula (a1-1-01) shown below which includes the structural
units represented by formulas (a1-1-1) to (a1-1-4), and structural units
represented by general formula (a1-1-02) shown below which includes the
structural units represented by formulas (a1-1-35) to (a1-1-41) are also
preferable.

##STR00055##

[wherein, R represents a hydrogen atom, a lower alkyl group or a
halogenated lower alkyl group; and R11 represents a lower alkyl
group.]

##STR00056##

[wherein, R represents a hydrogen atom, a lower alkyl group or a
halogenated lower alkyl group; R12 represents a lower alkyl group;
and h represents an integer of 1 to 3.]

[0190]In general formula (a1-1-01), R is as defined for R in general
formula (a1-0-1) shown above.

[0191]The lower alkyl group for R11 is as defined for the lower alkyl
group for R in general formula (a1-0-1) shown above, and is preferably a
methyl group or an ethyl group.

[0192]In general formula (a1-1-02), R is as defined for R in general
formula (a1-0-1) shown above.

[0193]The lower alkyl group for R12 is as defined for the lower alkyl
group for R in general formula (a1-0-1) shown above, is preferably a
methyl group or an ethyl group, and is most preferably an ethyl group, h
is preferably 1 or 2, and most preferably 2.

[0194]As the structural unit (a1), a single type of structural unit may be
used, or a combination of two or more types may be used.

[0195]In the component (A1), the amount of the structural unit (a1) based
on the combined total of all structural units constituting the component
(A1) is preferably 10 to 80 mol %, more preferably 20 to 70 mol %, and
still more preferably 25 to 50 mol %. By making the amount of the
structural unit (a1) at least as large as the lower limit of the
above-mentioned range, a pattern can be easily formed using a resist
composition prepared from the component (A1). On the other hand, by
making the amount of the structural unit (a1) no more than the upper
limit of the above-mentioned range, a good balance can be achieved with
the other structural units.

[0197]The term "lactone-containing cyclic group" refers to a cyclic group
including one ring containing a --O--C(O)-- structure (lactone ring). The
term "lactone ring" refers to a single ring containing a --O--C(O)--
structure, and this ring is counted as the first ring, A
lactone-containing cyclic group in which the only ring structure is the
lactone ring is referred to as a monocyclic group, and groups containing
other ring structures are described as polycyclic groups regardless of
the structure of the other rings.

[0198]When the copolymer (A1) is used for forming a resist film, the
lactone-containing cyclic group of the structural unit (a2) is effective
in improving the adhesion between the resist film and the substrate, and
increasing the compatibility with the developing solution containing
water.

[0199]As the structural unit (a2), there is no particular limitation, and
an arbitrary structural unit may be used.

[0200]Specific examples of lactone-containing monocyclic groups include
groups in which one hydrogen atom has been removed from y-butyrolactone.
Further, specific examples of lactone-containing polycyclic groups
include groups in which one hydrogen atom has been removed from a lactone
ring-containing bicycloalkane, tricycloalkane or tetracycloalkane.

[0201]More specifically, examples of the structural unit (a2) include
structural units represented by general formulas (a2-1) to (a2-5) shown
below.

##STR00057##

[wherein R represents a hydrogen atom, a lower alkyl group or a
halogenated lower alkyl group; R' represents a hydrogen atom, a lower
alkyl group, an alkoxy group of 1 to 5 carbon atoms, or a --COOR'' group;
R'' represents a hydrogen atom, or a linear, branched or cyclic alkyl
group of 1 to 15 carbon atoms; m represents an integer of 0 or 1; and A''
represents an alkylene group of 1 to 5 carbon atoms that may include an
oxygen atom or sulfur atom, an oxygen atom, or a sulfur atom.]

[0202]In general formulas (a2-1) to (a2-5), R is as defined for R in
general formula (a1-0-1) shown above.

[0203]The lower alkyl group for R' is as defined for the lower alkyl group
for R in general formula (a1-0-1) shown above.

[0204]When R'' represents a linear or branched alkyl group, the group
preferably contains 1 to 10 carbon atoms, and more preferably 1 to 5
carbon atoms.

[0205]When R'' represents a cyclic alkyl group, the group preferably
contains 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and
most preferably 5 to 10 carbon atoms. Examples include groups in which
one or more hydrogen atoms have been removed from a monocycloalkane or a
polycycloalkane such as a bicycloalkane, tricycloalkane or
tetracycloalkane, which may or may not be substituted with a fluorine
atom or a fluorinated alkyl group. Specific examples include groups in
which one or more hydrogen atoms have been removed from a monocycloalkane
such as cyclopentane or cyclohexane, or a polycycloalkane such as
adamantane, norbornane, isobornane, tricyclodecane or tetracyclododecane.

[0206]In general formulas (a2-1) to (a2-5), in consideration of industrial
availability, R' is preferably a hydrogen atom.

[0207]Specific examples of the alkylene group of 1 to 5 carbon atoms that
may include an oxygen atom or sulfur atom include a methylene group,
ethylene group, n-propylene group, isopropylene group, --O--CH2--,
--CH2--O--CH2--, --S--CH2--, and
--CH2--S--CH2--.

[0208]Specific examples of structural units represented by general
formulas (a2-1) to (a2-5) are shown below.

[0209]In the component (A1), as the structural unit (a2), one type of
structural unit may be used, or two or more types may be used in
combination.

[0210]Of these, at least one structural unit selected from the group
consisting of structural units represented by formulas (a2-1) to (a2-5)
is preferable, and at least one structural unit selected from the group
consisting of structural units represented by formulas (a2-1) to (a2-3)
is more preferable. Specifically, it is preferable to use at least one
structural unit selected from the group consisting of structural units
represented by formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-2-9),
(a2-2-10), (a2-3-1), (a2-3-2), (a2-3-9) and (a2-3-10).

[0211]As the structural unit (a2), one type of structural unit may be
used, or two or more types may be used in combination.

[0212]In the component (A1), the amount of the structural unit (a2) based
on the combined total of all structural units constituting the component
(A1) is preferably 5 to 60 mol %, more preferably 10 to 50 mol %, and
still more preferably 20 to 50 mol % By making the amount of the
structural unit (a2) at least as large as the lower limit of the
above-mentioned range, the effect of using the structural unit (a2) can
be satisfactorily achieved. On the other hand, by making the amount of
the structural unit (a2) no more than the upper limit of the
above-mentioned range, a good balance can be achieved with the other
structural units.

--Structural Unit (a3):

[0213]The structural unit (a3) is derived from an acrylate ester having a
polar group-containing aliphatic hydrocarbon group

[0214]By including the structural unit (a3) within the component (A1), the
hydrophilicity of the component (A1) is improved, and hence, the
compatibility of the component (A1) with the developing solution is
improved. As a result, the solubility of the exposed portions in an
alkali developing solution improves, which contributes to favorable
improvements in the resolution.

[0215]Examples of the polar group include a hydroxyl group, cyano group,
carboxyl group, or hydroxyalkyl group in which some of the hydrogen atoms
of the alkyl group have been substituted with fluorine atoms, although a
hydroxyl group is particularly desirable.

[0216]Examples of the aliphatic hydrocarbon group include linear or
branched hydrocarbon groups (and preferably alkylene groups) of 1 to 10
carbon atoms, and polycyclic aliphatic hydrocarbon groups (polycyclic
groups). These polycyclic groups can be selected appropriately from the
multitude of groups that have been proposed for the resins of resist
compositions designed for use with ArF excimer lasers. The polycyclic
group preferably has 7 to 30 carbon atoms.

[0217]Of the various possibilities, structural units derived from an
acrylate ester that includes an aliphatic polycyclic group containing a
hydroxyl group, cyano group, carboxyl group or a hydroxyalkyl group in
which some of the hydrogen atoms of the alkyl group have been substituted
with fluorine atoms are particularly desirable. Examples of the
polycyclic group include groups in which two or more hydrogen atoms have
been removed from a bicycloalkane, tricycloalkane or tetracycloalkane or
the like. Specific examples include groups in which two or more hydrogen
atoms have been removed from a polycycloalkane such as adamantane,
norbornane, isobornane, tricyclodecane or tetracyclododecane. Of these
polycyclic groups, groups in which two or more hydrogen atoms have been
removed from adamantane, norbornane or tetracyclododecane are preferred
industrially.

[0218]When the hydrocarbon group within the polar group-containing
aliphatic hydrocarbon group is a linear or branched hydrocarbon group of
1 to 10 carbon atoms, the structural unit (a3) is preferably a structural
unit derived from a hydroxyethyl ester of acrylic acid. On the other
hand, when the hydrocarbon group is a polycyclic group, structural units
represented by formulas (a3-1), (a3-2) and (a3-3) shown below are
preferable.

[0219][Chemical Formula 40]

[wherein, R is as defined above; j is an integer of 1 to 3; k is an
integer of 1 to 3; t' is an integer of 1 to 3; l is an integer of 1 to 5;
and s is an integer of 1 to 3.]

[0220]In formula (a3-1), j is preferably 1 or 2, and more preferably 1.
When j is 2, it is preferable that the hydroxyl groups be bonded to the
3rd and 5th positions of the adamantyl group. When j is 1, it is
preferable that the hydroxyl group be bonded to the 3rd position of the
adamantyl group.

[0221]j is preferably 1, and it is particularly desirable that the
hydroxyl group be bonded to the 3rd position of the adamantyl group.

[0222]In formula (a3-2), k is preferably 1. The cyano group is preferably
bonded to the 5th or 6th position of the norbornyl group.

[0223]In formula (a3-3), t' is preferably 1, l is preferably 1, and s is
preferably 1. Further, in formula (a3-3), it is preferable that a
2-norbornyl group or 3-norbornyl group be bonded to the terminal of the
carboxyl group of the acrylic acid. The fluorinated alkyl alcohol is
preferably bonded to the 5th or 6th position of the norbornyl group.

[0224]As the structural unit (a3), one type of structural unit may be
used, or two or more types may be used in combination.

[0225]The amount of the structural unit (a3) within the component (A1)
based on the combined total of all structural units constituting the
component (A1) is preferably 5 to 50 mol %, more preferably 5 to 40 mol
%, and still more preferably 5 to 25 mol %. By making the amount of the
structural unit (a3) at least as large as the lower limit of the
above-mentioned range, the effect of using the structural unit (a3) can
be satisfactorily achieved. On the other hands by making the amount of
the structural unit (a3) no more than the upper limit of the
above-mentioned range, a good balance can be achieved with the other
structural units.

--Structural Unit (a4):

[0226]The component (A1) may also include a structural unit (a4) which is
other than the above-mentioned structural units (a1) to (a3), as long as
the effects of the present invention are not impaired.

[0227]As the structural unit (a4), any other structural unit which cannot
be classified as one of the above structural units (a1) to (a3) can be
used without any particular limitations, and any of the multitude of
conventional structural units used within resist resins for ArF excimer
lasers or KrF excimer lasers (and particularly for ArF excimer lasers)
can be used.

[0228]As the structural unit (a4), a structural unit which contains a
non-acid-dissociable aliphatic polycyclic group, and is also derived from
an acrylate ester is preferable. Examples of this polycyclic group
include the same groups as those described above in connection with the
aforementioned structural unit (a1), and any of the multitude of
conventional polycyclic groups used within the resin component of resist
compositions for ArF excimer lasers or KrF excimer lasers (and
particularly for ArF excimer lasers) can be used.

[0229]In consideration of industrial availability and the like, at least
one polycyclic group selected from amongst a tricyclodecanyl group,
adamantyl group, tetracyclododecanyl group, isobornyl group and norbornyl
group is particularly desirable. These polycyclic groups may be
substituted with a linear or branched alkyl group of 1 to 5 carbon atoms.

[0230]Specific examples of the structural unit (a4) include units with
structures represented by general formulas (a4-1) to (a4-5) shown below.

##STR00066##

(wherein, R is as defined above.)

[0231]When the structural unit (a4) is included in the component (A1), the
amount of the structural unit (a4) within the component (A1) based on the
combined total of all the structural units that constitute the component
(A1) is preferably within a range from 1 to 30 mol %, and more preferably
from 10 to 20 mol %.

[0232]In the present invention, the component (A1) preferably includes a
copolymer having the structural units (a1), (a2) and (a3). Examples of
such a copolymer include a copolymer consisting of the structural units
(a1) and (a2) and (a3), and a copolymer consisting of the structural
units (a1), (a2), (a3) and (a4).

[0233]The component (A1) can be obtained, for example, by a conventional
radical polymerization or the like of the monomers corresponding with
each of the structural units, using a radical polymerization initiator
such as azobisisobutyronitrile (AIBN).

[0234]Furthermore, in the component (A1), by using a chain transfer agent
such as HS--CH2--CH2--CH2--C(CF3)2--OH during
the above polymerization, a --C(CF3)2--OH group can be
introduced at the terminals of the component (A1). Such a copolymer
having an introduced hydroxyalkyl group in which some of the hydrogen
atoms of the alkyl group are substituted with fluorine atoms is effective
in reducing developing defects and LER (line edge roughness: unevenness
of the side walls of a line pattern).

[0235]The weight average molecular weight (Mw) (the polystyrene equivalent
value determined by gel permeation chromatography) of the component (A1)
is not particularly limited, but is preferably 2,000 to 50,000, more
preferably 3,000 to 30,000, and most preferably 5,000 to 20,000. By
making the weight average molecular weight no more than the upper limit
of the above-mentioned range, the component (A1) exhibits satisfactory
solubility in a resist solvent when used as a resist. On the other hand,
by making the weight average molecular weight at least as large as the
lower limit of the above-mentioned range, dry etching resistance and
cross-sectional shape of the resist pattern becomes satisfactory.

[0236]Further, the dispersity (Mw/Mn) is preferably 1.0 to 5,0, more
preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. Here, Mn is the
number average molecular weight.

[Component (A2)]

[0237]As the component (A2), a low molecular weight compound that has a
molecular weight of at least 500 but less than 2,000, contains a
hydrophilic group, and also contains an acid dissociable, dissolution
inhibiting group such as the groups exemplified above in the description
of the component (A1) is preferred. Specific examples include compounds
containing a plurality of phenol structures, in which some of the
hydroxyl group hydrogen atoms have been substituted with the acid
dissociable, dissolution inhibiting groups exemplified above in the
description of the component (A1).

[0238]Preferred examples of the component (A2) include low molecular
weight phenol compounds that are known, for example, as sensitizers or
heat resistance improvers for use in non-chemically amplified g-line or
i-line resists, wherein some of the hydroxyl group hydrogen atoms of
these compounds have been substituted with the types of acid dissociable,
dissolution inhibiting groups exemplified above in the description of the
component (A1), and any of these compounds may be used.

[0239]Specific examples of the low molecular weight phenol compounds
include bis(4-hydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane,
2-(4-hydroxyphenyl)-2-(4'-hydroxyphenyl)propane,
2-(2,3,4-trihydroxyphenyl)-2-(2',3',4'-trihydroxyphenyl)propane,
tris(4-hydroxyphenyl)methane,
bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane,
bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane,
bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane,
bis(4-hydroxy-2,5-dimethylphenyl)-3,4-dihydroxyphenylmethane,
bis(4-hydroxy-3-methylphenyl)-3,4-dihydroxyphenylmethane,
bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-4-hydroxyphenylmethane,
bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-3,4-dihydroxyphenylmethane,
1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene-
, and dimers, trimers and tetramers of formalin condensation products of
phenols such as phenol, m-cresol, p-cresol and xylenol. Of course, this
is not a restrictive list.

[0240]There are no particular limitations on the acid dissociable,
dissolution inhibiting group, and examples include the groups exemplified
above.

[0241]As the component (A), one type of component may be used alone, or
two or more types may be used in combination.

[0242]In the resist composition of the present invention, the amount of
the component (A) can be appropriately adjusted depending on the
thickness of the resist film to be formed.

[0243]<Component (B)>

[0244]As the component (B), there is no particular limitation, and any of
the known acid generators used in conventional chemically amplified
resist compositions can be used. Examples of these acid generators are
numerous, and include onium salt-based acid generators such as iodonium
salts and sulfonium salts; oxime sulfonate-based acid generators;
diazomethane-based acid generators such as bisalkyl or bisaryl sulfonyl
diazomethanes and poly(bis-sulfonyl)diazomethanes;
nitrobenzylsulfonate-based acid generators; iminosulfonate-based acid
generators; and disulfone-based acid generators.

[0245]As the onium salt-based acid generator, a compound represented by
general formula (b-1) or (b-2) shown below can be used.

##STR00067##

[wherein, R1'' to R3'', R5'' and R6'' each
independently represents an aryl group or alkyl group, wherein two of
R1'' to R3'' in formula (b-1) may be bonded to each other to
form a ring with the sulfur atom in the formula; and R4'' represents
a linear, branched or cyclic alkyl group or fluorinated alkyl group;
provided that at least one of R1'' to R3'' represents an aryl
group, and at least one of R5'' and R6'' represents an aryl
group.]

[0246]In formula (b-1), R1'' to R3'' each independently
represents an aryl group or an alkyl group. Two of R1'' to R3''
in formula (b-1) may be bonded to each other to form a ring with the
sulfur atom in the formula.

[0247]Further, among R1'' to R3'', at least one group represents
an aryl group. Among R1'' to R3'', two or more groups are
preferably aryl groups, and it is particularly desirable that all of
R1'' to R3'' are aryl groups.

[0248]The aryl group for R1'' to R3'' is not particularly
limited. For example, an aryl group having 6 to 20 carbon atoms may be
used, in which some or all of the hydrogen atoms of the aryl group may or
may not be substituted with alkyl groups, alkoxy groups, halogen atoms or
hydroxyl groups. The aryl group is preferably an aryl group having 6to 10
carbon atoms because it can be synthesized at a low cost. Specific
examples thereof include a phenyl group and a naphthyl group.

[0249]The alkyl group with which hydrogen atoms of the aryl group may be
substituted is preferably an alkyl group having 1 to 5 carbon atoms, and
most preferably a methyl group, ethyl group, propyl group, n-butyl group
or tert-butyl group.

[0250]The alkoxy group with which hydrogen atoms of the aryl group may be
substituted is preferably an alkoxy group having 1 to 5 carbon atoms,
more preferably a methoxy group, ethoxy group, n-propoxy group,
iso-propoxy group, n-butoxy group or tert-butoxy group, and most
preferably a methoxy group or an ethoxy group.

[0251]The halogen atom with which hydrogen atoms of the aryl group may be
substituted is preferably a fluorine atom.

[0252]The alkyl group for R1'' to R3'' is not particularly
limited and includes, for example, a linear, branched or cyclic alkyl
group having 1 to 10 carbon atoms. In terms of achieving excellent
resolution, the alkyl group preferably has 1 to 5 carbon atoms. Specific
examples thereof include a methyl group, ethyl group, n-propyl group,
isopropyl group, n-butyl group, isobutyl group, n-pentyl group,
cyclopentyl group, hexyl group, cyclohexyl group, nonyl group or decanyl
group. A methyl group is most preferable because it is excellent in
resolution and can be synthesized at a low cost.

[0253]It is particularly desirable that each of R1'' to R3'' is
a phenyl group or a naphthyl group.

[0254]When two of R1'' to R3'' in formula (b-1) are bonded to
each other to form a ring with the sulfur atom shown in the formula, it
is preferable that the two of R1'' to R3'' form a 3- to
10-membered ring including the sulfur atom, and it is particularly
desirable that the two of R1'' to R3'' form a 5- to 7-membered
ring including the sulfur atom.

[0255]When two of R1'' to R3'' in formula (b-1) are bonded to
each other to form a ring with the sulfur atom shown in the formula, the
remaining one of R1'' to R3'' is preferably an aryl group. As
examples of the aryl group, the same as the above-mentioned aryl groups
for R1'' to R3'' can be exemplified.

[0256]R4'' represents a linear, branched or cyclic alkyl group or
fluorinated alkyl group. The linear or branched alkyl group preferably
has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most
preferably 1 to 4 carbon atoms.

[0257]The cyclic alkyl group is preferably a cyclic group as described for
R1'', having 4 to 15 carbon atoms, more preferably 4 to 10 carbon
atoms, and most preferably 6 to 10 carbon atoms.

[0258]The fluorinated alkyl group preferably has 1 to 10 carbon atoms,
more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon
atoms. Further, the fluorination ratio of the fluorinated alkyl group
(the percentage of fluorine atoms within the alkyl group) is preferably
from 10 to 100%, more preferably from 50 to 100%, and it is particularly
desirable that all hydrogen atoms are substituted with fluorine atoms
(namely, the fluorinated alkyl group is a perfluoroalkyl group) because
the acid strength increases.

[0259]R4'' is most preferably a linear or cyclic alkyl group or
fluorinated alkyl group.

[0260]In formula (b-2), R5'' and R6'' each independently
represents an aryl group or an alkyl group. At least one of R5'' and
R6'' represents an aryl group. It is preferable that R5'' and
R6'' both represent aryl groups.

[0261]As the aryl group for R5'' and R6'', the same aryl groups
as those mentioned above for R1'' to R3'' in formula (b-1) can
be exemplified.

[0262]As the alkyl group for R5'' and R6'', the same alkyl
groups as those mentioned above for R1'' to R3'' in formula
(b-1) can be exemplified.

[0263]It is particularly desirable that both of R5'' and R6''
represent phenyl groups.

[0264]As R4'' in formula (b-2), the same groups as those mentioned
above for R4'' in formula (b-1) can be exemplified.

[0266]It is also possible to use onium salts in which the anion moiety of
these onium salts has been replaced by meflianesulfonate,
n-propanesulfonate, n-butanesulfonate, or n-octanesulfonate.

[0267]Further, onium salt-based acid generators in which the anion moiety
in general formula (b-1) or (b-2) is replaced by an anion moiety
represented by general formula (b-3) or (b-4) shown below (the cation
moiety is the same as (b-1) or (b-2)) may also be used.

##STR00068##

[wherein, X'' represents an alkylene group of 2 to 6 carbon atoms in which
at least one hydrogen atom has been substituted with a fluorine atom; and
Y'' and Z'' each independently represents an alkyl group of 1 to 10
carbon atoms in which at least one hydrogen atom has been substituted
with a fluorine atom.]

[0268]X'' represents a linear or branched alkylene group in which at least
one hydrogen atom has been substituted with a fluorine atom, and the
alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms,
and most preferably 3 carbon atoms.

[0269]Y'' and Z'' each independently represents a linear or branched alkyl
group in which at least one hydrogen atom has been substituted with a
fluorine atom, and the alkyl group has 1 to 10 carbon atoms, preferably 1
to 7 carbon atoms, and more preferably 1 to 3 carbon atoms.

[0270]The smaller the number of carbon atoms within the alkylene group of
X'' or within the alkyl group of Y'' and Z'' within the above ranges for
the number of carbon atoms, the better the solubility in a resist
solvent.

[0271]Further, in the alkylene group of X'' or the alkyl group of Y'' and
Z'', it is preferable that the number of hydrogen atoms substituted with
fluorine atoms is as large as possible, as the acid strength increases,
and the transparency to high energy radiation of 200 nm or less or
electron beam is improved. The fluorination ratio of the alkylene group
or alkyl group is preferably from 70 to 100%, more preferably from 90 to
100%, and it is particularly desirable that the alkylene group or alkyl
group be a perfluoroalkylene group or perfluoroalkyl group in which all
the hydrogen atoms are substituted with fluorine atoms.

[0272]Furthermore, as the onium salt-based acid generator, a sulfonium
salt having a cation moiety represented by general formula (b-5) or (b-6)
shown below may also be used.

##STR00069##

[wherein R41 to R46 each independently represents an alkyl
group, an acetyl group, an alkoxy group, a carboxyl group, a hydroxyl
group or a hydroxyalkyl group; n1 to n5 each independently
represents an integer of 0 to 3; and n6 represents an integer of 0
to 2.]

[0273]With respect to R41 to R46, the alkyl group is preferably
an alkyl group of 1 to 5 carbon atoms, more preferably a linear or
branched alkyl group, and most preferably a methyl group, ethyl group,
propyl group, isopropyl group, n-butyl group or tert butyl group.

[0274]The alkoxy group is preferably an alkoxy group of 1 to 5 carbon
atoms, more preferably a linear or branched alkoxy group, and most
preferably a methoxy group or ethoxy group.

[0275]The hydroxyalkyl group is preferably an aforementioned alkyl group
in which one or more hydrogen atoms have been substituted with hydroxy
groups, and examples thereof include a hydroxymethyl group, hydroxyethyl
group and hydroxypropyl group.

[0276]When the subscripts n1 to n6 of R41 to R46
represent an integer of 2 or more, the plurality of R41 to R46
may be the same or different.

[0277]m is preferably 0 to 2, more preferably 0 or 1, and still more
preferably 0.

[0278]It is preferable that n2 and n3 each independently
represents 0 or 1, and more preferably 0.

[0279]n4 is preferably 0 to 2, and more preferably 0 or 1.

[0280]n5 is preferably 0 or 1, and more preferably 0.

[0281]n6 is preferably 0 or 1, and more preferably 1.

[0282]The anion moiety of the sulfonium salt having a cation moiety
represented by general formula (b-5) or (b-6) is not particularly
limited, and the same anion moieties as those used within previously
proposed onium salt-based acid generators may be used. Examples of such
anion moieties include fluorinated alkylsulfonate ions such as anion
moieties (R4''SO3.sup.-) for onium salt-based acid generators
represented by general formula (b-1) or (b-2) shown above; and anion
moieties represented by general formula (b-3) or (b-4) shown above. Among
these, fluorinated alkylsulfonate ions are preferable, more preferably
fluorinated alkylsulfonate ions of 1 to 4 carbon atoms, and linear
perfluoroalkylsulfonate ions of 1 to 4 carbon atoms are particularly
desirable. Specific examples include a trifluoromethylsulfonate ion,
heptafluoro-n-propylsulfonate ion and nonafluoro-n-butylsulfonate ion.

[0283]In the present description, an oxime sulfonate-based acid generator
is a compound having at least one group represented by general formula
(B-1) shown below, and has a feature of generating acid by irradiation.
Such oxime sulfonate-based acid generators are widely used for a
chemically amplified resist composition, and can be selected as
appropriate.

##STR00070##

[wherein R31 and R32 each independently represents an organic
group.]

[0284]The organic group for R31 and R32 refers to a group
containing a carbon atom, and may include atoms other than carbon atoms
(such as a hydrogen atom, an oxygen atom, a nitrogen atom, a sulfur atom,
or a halogen atom (such as a fluorine atom and a chlorine atom) and the
like).

[0285]As the organic group for R31, a linear, branched, or cyclic
alkyl group or an aryl group is preferable. The alkyl group or the aryl
group may have a substituent. The substituent is not particularly
limited, and examples thereof include a fluorine atom and a linear,
branched or cyclic alkyl group having 1 to 6 carbon atoms. The expression
"have a substituent" means that some or all of the hydrogen atoms of the
alkyl group or the aryl group are substituted with substituents.

[0286]The alkyl group preferably has 1 to 20 carbon atoms, more preferably
1 to 10 carbon atoms, still more preferably 1 to 8 carbon atoms, still
more preferably 1 to 6 carbon atoms, and most preferably 1 to 4 carbon
atoms. As the alkyl group, a partially or completely halogenated alkyl
group (hereinafter, sometimes referred to as a "halogenated alkyl group")
is particularly desirable. The "partially halogenated alkyl group" refers
to an alkyl group in which some of the hydrogen atoms are substituted
with halogen atoms, and the "completely halogenated alkyl group" refers
to an alkyl group in which all of the hydrogen atoms are substituted with
halogen atoms. Examples of the halogen atom include a fluorine atom, a
chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is
particularly desirable. In other words, the halogenated alkyl group is
preferably a fluorinated alkyl group.

[0287]The aryl group preferably has 4 to 20 carbon atoms, more preferably
4 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms. As the
aryl group, a partially or completely halogenated aryl group is
particularly desirable. The "partially halogenated aryl group" refers to
an aryl group in which some of the hydrogen atoms are substituted with
halogen atoms, and the "completely halogenated aryl group" refers to an
aryl group in which all of hydrogen atoms are substituted with halogen
atoms.

[0288]As R31, an alkyl group of 1 to 4 carbon atoms which has no
substituent or a fluorinated alkyl group of 1 to 4 carbon atoms is
particularly desirable.

[0289]As the organic group for R32, a linear, branched, or cyclic
alkyl group, an aryl group, or a cyano group is preferable. Examples of
the alkyl group and the aryl group for R32 are the same as those of
the alkyl group and the aryl group for R31.

[0290]As R32, a cyano group, an alkyl group of 1 to 8 carbon atoms
having no substituent, or a fluorinated alkyl group of 1 to 8 carbon
atoms is particularly desirable.

[0291]Preferred examples of the oxime sulfonate-based acid generator
include compounds represented by general formula (B-2) or (B-3) shown
below.

##STR00071##

[wherein, R33 represents a cyano group, an alkyl group having no
substituent, or a halogenated alkyl group; R34 represents an aryl
group; and R35 represents an alkyl group having no substituent, or a
halogenated alkyl group.]

##STR00072##

[wherein R36 represents a cyano group, an alkyl group having no
substituent, or a halogenated alkyl group; R37 represents a divalent
or trivalent aromatic hydrocarbon group; R38 represents an alkyl
group having no substituent, or a halogenated alkyl group; and p''
represents 2 or 3.]

[0292]In general formula (B-2), the alkyl group having no substituent or
the halogenated alkyl group for R33 preferably has 1 to 10 carbon
atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6
carbon atoms.

[0293]As R33, a halogenated alkyl group is preferable, and a
fluorinated alkyl group is more preferable.

[0294]The fluorinated alkyl group for R33 preferably has 50% or more
of the hydrogen atoms thereof fluorinated, more preferably 70% or more,
and most preferably 90% or more.

[0295]Examples of the aryl group for R34 include groups in which one
hydrogen atom has been removed from an aromatic hydrocarbon ring, such as
a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an
anthryl group and a phenanthryl group, and heteroaryl groups in which
some of the carbon atoms constituting the ring(s) of these groups are
substituted with hetero atoms such as an oxygen atom, a sulfur atom or a
nitrogen atom. Of these, a fluorenyl group is preferable.

[0296]The aryl group for R34 may have a substituent such as an alkyl
group of 1 to 10 carbon atoms, a halogenated alkyl group, or an alkoxy
group. The alkyl group and halogenated alkyl group as the substituent
preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon
atoms. The halogenated alkyl group is preferably a fluorinated alkyl
group.

[0297]The alkyl group having no substituent or the halogenated alkyl group
for R35

[0298]preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon
atoms, and most preferably 1 to 6 carbon atoms.

[0299]As R35, a halogenated alkyl group is preferable, and a
fluorinated alkyl group is more preferable.

[0300]In terms of enhancing the strength of the acid generated, the
fluorinated alkyl

[0301]group for R35 preferably has 50% or more of the hydrogen atoms
fluorinated, more preferably 70% or mores still more preferably 90% or
more. A completely fluorinated alkyl group in which 100% of the hydrogen
atoms are substituted with fluorine atoms is particularly desirable.

[0302]In general formula (B-3), the alkyl group having no substituent and
the halogenated alkyl group for R36 are the same as the alkyl group
having no substituent and the halogenated alkyl group for R33 in
general formula (B-2).

[0303]Examples of the divalent or trivalent aromatic hydrocarbon group for
R37 include groups in which one or two hydrogen atoms have been
removed from the aryl group for R34 in general formula (B-2).

[0304]As the alkyl group having no substituent or the halogenated alkyl
group for R38, the same alkyl groups having no substituent or the
halogenated alkyl groups exemplified above for R35 in general
formula (B-2) can be used.

[0310]Further, diazomethane-based acid generators disclosed in Japanese
Unexamined Patent Application, First Publication No. Hei 11-035551,
Japanese Unexamined Patent Application, First Publication No. Hei
11-035552 and Japanese Unexamined Patent Application, First Publication
No. Hei 11-035573 may also be used favorably.

[0311]Furthermore, as poly(bis-sulfonyl)diazomethanes, those disclosed in
Japanese Unexamined Patent Application, First Publication No. Hei
11-322707, including 1,3-bis(phenylsulfonyldiazomethylsulfonyl)propane,
1,4-bis(phenylsulfonyldiazomethylsulfonyl)butane,
1,6-bis(phenylsulfonyldiazomethylsulfonyl)hexane,
1,10-bis(phenylsulfonyldiazomethylsulfonyl)decane,
1,2-bis(cyclohexylsulfonyldiazomethylsulfonyl)ethane,
1,3-bis(cyclohexylsulfonyldiazomethylsulfonyl)propane,
1,6-bis(cyclohexylsulfonyldiazomethylsulfonyl)hexane, and
1,10-bis(cyclohexylsulfonyldiazomethylsulfonyl)decane, may be
exemplified.

[0312]As the component (B), one type of acid generator may be used, or two
or more types may be used in combination.

[0313]In the present invention, as the component (B), it is preferable to
use an onium salt-based acid generator having a fluorinated alkylsulfonic
acid ion that may have a substituent as the anion moiety.

[0314]The amount of the component (B) within the resist composition for
immersion exposure according to the present invention is preferably from
0.5 to 30 parts by weight, and more preferably from 1 to 10 parts by
weight, relative to 100 parts by weight of the component (A). When the
amount of the component (B) is within the above-mentioned range,
formation of a resist pattern can be satisfactorily performed. Further,
by virtue of the above-mentioned range, a uniform solution can be
obtained and the storage stability becomes satisfactory.

<Component (C)>

[0315]The component (C) is the fluorine-containing compound (C) of the
present invention described above.

[0316]As the component (C), one type of fluorine-containing compound may
be used, or two or more types may be used in combination.

[0317]The amount of the component (C) within the resist composition for
immersion exposure according to the present invention is preferably from
0.1 to 20 parts by weight, more preferably from 0.5 to 15 parts by
weight, still more preferably from 0.5 to 10 parts by weight, and most
preferably from 1 to 5 parts by weight, relative to 100 parts by weight
of the component (A). By making the amount of the component (C) at least
as large as the lower limit of the above-mentioned range, the
hydrophobicity of the resist film formed using the resist composition for
immersion exposure improves, yielding a level of hydrophobicity that is
ideal for immersion exposure. On the other hand, by making the amount of
the component (C) no more than the upper limit of the above-mentioned
range, the lithography properties are improved.

<Optional Components>

[0318]In order to improve factors such as the resist pattern shape and the
post exposure stability of the latent image formed by the pattern-wise
exposure of the resist layer, it is preferable that the resist
composition for immersion exposure according to the present invention
further includes a nitrogen-containing organic compound (D) (hereafter
referred to as "component (D)") as an optional component.

[0319]A multitude of these components (D) have already been proposed, and
any of these known compounds may be used, although an aliphatic amine,
and particularly a secondary aliphatic amine or tertiary aliphatic amine
is preferable. An "aliphatic amine" is an amine having one or more
aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon
atoms.

[0320]Examples of these aliphatic amines include amines in which at least
one hydrogen atom of ammonia (NFH3) has been substituted with an
alkyl group or hydroxyalkyl group of no more than 12 carbon atoms (that
is, alkylamines or alkyl alcohol amines), and cyclic amines.

[0321]Specific examples of the alkylamines or alkyl alcohol amines include
monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,
n-nonylamine, and n-decylamine; dialkylamines such as diethylamine,
di-n-propylamine, di-n-heptylamine, di-n-octylamine, and
dicyclohexylamine; trialkylamines such as trimemylamine, triethylamine,
tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine,
tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine,
tri-n-decanylamine, and tri-n-dodecylamine; and alkyl alcohol amines such
as diethanolamine, triethanolamine, diisopropanolamine,
triisopropanolamine, di-n-octanolamine, and tri-n-octanolamine. Among
these, trialkylamines of 5 to 10 carbon atoms are preferable, and
tri-n-pentylamine is particularly desirable.

[0322]Examples of the cyclic amines include heterocyclic compounds
containing a nitrogen atom as a hetero atom. The heterocyclic compound
may be a monocyclic compound (aliphatic monocyclic amine), or a
polycyclic compound (aliphatic polycyclic amine).

[0323]Specific examples of the aliphatic monocyclic amine include
piperidine and piperazine.

[0325]Either one type of amine may be used, or two or more types may be
used in combination.

[0326]The component (D) is typically used in an amount within a range from
0.01 to 5.0 parts by weight, relative to 100 parts by weight of the
component (A).

[0327]Furthermore, in the resist composition for immersion exposure
according to the present invention, for preventing any deterioration in
sensitivity, and improving the resist pattern shape and the post exposure
stability of the latent image formed by the pattern-wise exposure of the
resist layer, at least one compound (E) (hereafter referred to as
"component (E)") selected from the group consisting of organic carboxylic
acids, and phosphorus oxo acids and derivatives thereof can be added.

[0330]Examples of oxo acid derivatives include esters in which a hydrogen
atom within an above-mentioned oxo acid is substituted with a hydrocarbon
group. Examples of the hydrocarbon group include an alkyl group of 1 to 5
carbon atoms and an aryl group of 6 to 15 carbon atoms.

[0331]Examples of phosphoric acid derivatives include phosphoric acid
esters such as di-n-butyl phosphate and diphenyl phosphate.

[0333]Examples of phosphinic acid derivatives include phosphinic acid
esters such as phenylphosphinic acid.

[0334]As the component (E), one type of component may be used alone, or
two or more types may be used in combination.

[0335]The component (E) is typically used in an amount within a range from
0.01 to 5.0 parts by weight, relative to 100 parts by weight of the
component (A).

[0336]If desired, other miscible additives can also be added to the resist
composition for immersion exposure according to the present invention.
Examples of such miscible additives include additive resins for improving
the performance of the resist film, surfactants for improving the
applicability, dissolution inhibitors, plasticizers, stabilizers,
colorants, halation prevention agents, and dyes.

<Organic Solvent (S)>

[0337]The resist composition for immersion exposure according to the
present invention can be prepared by dissolving the materials for the
resist composition in an organic solvent (hereafter, frequently referred
to as "component (S)").

[0338]The component (S) may be any organic solvent which can dissolve the
respective components to give a uniform solution, and any one or more
kinds of organic solvents can be appropriately selected from those which
have been conventionally known as solvents for a chemically amplified
resist.

[0342]Further, among the mixed solvents, a mixed solvent obtained by
mixing PGMEA with a polar solvent is preferable. The mixing ratio (weight
ratio) of the mixed solvent can be appropriately determined, taking into
consideration the compatibility of the PGMEA with the polar solvent, but
is preferably in a range from 1:9 to 9:1, and more preferably from 2:8 to
8:2.

[0343]Specifically, when EL is mixed as the polar solvent, the PGMEA:EL
weight ratio is preferably from 1:9 to 9:1, and more preferably from 2:8
to 8:2. Alternatively, when PGME is mixed as the polar solvent, the
PGMEA:PGME is preferably from 1:9 to 9:1, more preferably from 2:8 to
8:2, and still more preferably 3:7 to 7:3.

[0344]Further, as the component (S), a mixed solvent of at least one of
PGMEA and EL with γ-butyrolactone is also preferable. The mixing
ratio (former:latter) of such a mixed solvent is preferably from 70:30 to
95:5.

[0345]The amount of the component (S) is not particularly limited, and is
adjusted appropriately to a concentration that enables application of a
coating solution to a substrate in accordance with the thickness of the
coating film. In general, the organic solvent is used in an amount that
yields a solid content for the resist composition that is within a range
from 2 to 20% by weight, and preferably from 5 to 15% by weight.

[0346]Dissolving of the materials for a resist composition in the
component (S) can be conducted by simply mixing and stirring each of the
above components together using conventional methods, and where required,
the composition may also be mixed and dispersed using a dispersion device
such as a dissolver, a homogenizer, or a triple roll mill. Furthermore,
following mixing, the composition may also be filtered using a mesh, or a
membrane filter or the like.

[0347]The resist composition for immersion exposure according to the
present invention has the properties required of a resist composition
used in immersion lithography, namely, favorable lithography properties
and favorable properties (particularly hydrophobicity) for use within an
immersion exposure process, and can therefore be used very favorably for
immersion exposure.

[0348]A resist film formed using the resist composition for immersion
exposure according to the present invention contains the component (C)
described above (namely, the fluorine-containing compound (C) of the
present invention).

[0349]This component (C) has a high hydrophobicity by virtue of containing
a fluorine atom, and also exhibits a property wherein the hydrophilicity
increases under basic conditions by virtue of containing a --O--R2
group. This increase in hydrophilicity is because under the action of a
base (an alkali developing solution), the --R2 group dissociates,
forming a hydrophilic (--OH) group.

[0350]Accordingly, a resist film formed using a resist composition for
immersion exposure of the present invention that includes the component
(C) together with the component (A) and the component (B) exhibits a high
level of hydrophobicity prior to contact with an alkali developing
solution (for example, during the immersion exposure), but then develops
increased hydrophilicity upon contact with the alkali developing
solution.

[0351]In this manner, because the hydrophobicity is high during the
immersion exposure, a resist film formed using the resist composition for
immersion exposure according to the present invention exhibits an
extremely favorable water tracking ability, which is required when the
immersion exposure is performed using a scanning-type immersion exposure
apparatus such as that disclosed in Non-Patent Document 1.

[0352]Further, because the hydrophilicity is increased during alkali
developing, the resist composition for immersion exposure according to
the present invention can effectively reduce defects during the immersion
exposure, In other words, when immersion exposure of a resist film is
conducted during immersion lithography, the solubility of the exposed
portions within an alkali developing solution changes. For example, in
the case of a positive resist composition, the solubility of the exposed
portions in an alkali developing solution increases, whereas in the case
of a negative resist composition, the solubility of the exposed portions
in an alkali developing solution decreases. Then, when alkali developing
is conducted, the exposed portions are removed in the case of the
positive composition, and the unexposed portions are removed in the case
of the negative composition, in either case leading to the formation of a
resist pattern.

[0353]During this process, the surface of those portions of the resist
film that are not irradiated during the immersion exposure (for example,
the unexposed portions of a positive resist) are prone to developing
defects caused by the immersion medium such as water (such as water mark
defects) following developing. However, because a resist film formed
using the resist composition for immersion exposure according to the
present invention exhibits increased hydrophilicity during developing, it
is able to reduce the occurrence of these defects.

[0354]Further, by using the resist composition for immersion exposure
according to the present invention, substance elution from the resist
film during immersion exposure can be suppressed.

[0355]As described above, immersion exposure is a technique that includes
a step of conducting exposure (immersion exposure) in a state where the
region between the lens and the resist film formed on the wafer, which
has conventionally been filled with air or an inert gas such as nitrogen,
is filled with a solvent (a liquid immersion medium) having a larger
refractive index than the refractive index of air. In immersion exposure,
when the resist film and the immersion solvent make contact, elution of
substances within the resist film (such as the component (B) and the
component (D)) into the immersion solvent (namely, substance elution)
tends to occur. This substance elution causes phenomena such as
degeneration of the resist layer and variation in the refractive index of
the immersion solvent, causing a deterioration in the lithography
properties.

[0356]The amount of this substance elution is affected by the properties
of the resist film surface (such as the hydrophilicity or
hydrophobicity). Accordingly, it is thought that by increasing the
hydrophobicity of the resist film surface, the degree of substance
elution can be reduced.

[0357]A resist film formed using the resist composition for immersion
exposure according to the present invention includes the fluorine
atom-containing component (C), and therefore has a higher level of
hydrophobicity prior to exposure and developing than a resist film that
does not include the component (C). Accordingly, the resist composition
for immersion exposure according to the present invention can inhibit
substance elution during immersion exposure.

[0358]Because it enables suppression of substance elution, using the
resist composition for immersion exposure of the present invention also
enables suppression of degeneration of the resist film and variation in
the refractive index of the immersion solvent during immersion exposure.
By suppressing fluctuation in the refractive index of the immersion
solvent, the shape and the like of the resulting resist pattern can be
improved. Further, staining of the lens of the exposure apparatus can
also be reduced. As a result, protective measures for preventing such
staining need not be performed, which contributes to a simplification of
both the process and the exposure apparatus.

[0359]Further, a resist film formed using the resist composition for
immersion exposure according to the present invention is resistant to
swelling water, meaning a very fine resist pattern can be formed with
superior precision.

[0360]Furthermore, the resist composition for immersion exposure according
to the present invention also exhibits favorable lithography properties
such as sensitivity, resolution and etching resistance, and when used as
a resist in an actual immersion exposure, is capable of forming a
favorable resist pattern without any practical difficulties. For example,
by using the resist composition for immersion exposure according to the
present invention, a very fine resist pattern with dimensions of not more
than 120 nm can be formed.

[0361]The hydrophobicity of a resist film can be evaluated by measuring
the contact angles relative to water, such as the static contact angle
(the contact angle between the surface of a water droplet on the resist
film in a horizontal state and the resist film surface), and the dynamic
contact angles (including the contact angle at which a water droplet
starts to slide when the resist film is inclined (the sliding angle), the
contact angle at the front-end point of the water droplet in the sliding
direction (the advancing angle), and the contact angle at the rear-end
point of the water droplet in the sliding direction (the receding
angle)). For example, the higher the hydrophobicity of the resist film,
the larger the static contact angle, the advancing angle and the receding
angle, and the smaller the sliding angle.

[0362]As shown in FIG. 1, when a flat surface 2 with a liquid droplet 1
placed thereon is gradually inclined, the advancing angle describes the
angle θ1 between the surface of the liquid droplet at the
bottom edge 1a of the liquid droplet 1 and the flat surface 2 when the
liquid droplet 1 starts to move (slide) down the flat surface 2. Further,
at this point (the point when the liquid droplet 1 starts to move (slide)
down the flat surface 2), the angle θ2 between the surface of
the liquid droplet at the top edge 1b of the liquid droplet 1 and the
flat surface 2 is the receding angle, and the inclination angle
θ3 of the flat surface 2 is the sliding angle.

[0363]In the present description, the advancing angle, the receding angle,
and the sliding angle are measured in the following manner.

[0364]First, a resist composition solution is spin-coated onto a silicon
substrate, and is then heated at a temperature of 110° C. for 60
seconds to form a resist film.

[0366]For a resist film obtained using the resist composition for
immersion exposure according to the present invention, the receding angle
measured prior to immersion exposure and developing is preferably 50
degrees or more, more preferably from 50 to 150 degrees, still more
preferably from 50 to 130 degrees, and most preferably from 53 to 100
degrees. When the receding angle is at least as large as the lower limit
of the above-mentioned range, the suppression effect on substance elution
during the immersion exposure is enhanced. The reason for this has not
been elucidated yet, but it is presumed that one of the main reasons is
related to the hydrophobicity of the resist film. More specifically, it
is presumed that since an aqueous substance such as water is used as the
immersion medium, higher hydrophobicity has an influence on the swift
removal of the immersion medium from the surface of the resist film after
the immersion exposure. On the other hand, when the receding angle is no
higher than the upper limit of the above-mentioned range, the lithography
properties become satisfactory.

[0367]For similar reasons, for a resist film obtained using the resist
composition for immersion exposure according to the present invention,
the static contact angle measured prior to immersion exposure and
developing is preferably 60 degrees or more, more preferably from 63 to
95 degrees, and most preferably from 65 to 95 degrees.

[0368]Furthermore, for a resist film obtained using the resist composition
for immersion exposure according to the present invention, the sliding
angle measured prior to immersion exposure and developing is preferably
no more than 36 degrees, more preferably from 10 to 36 degrees, still
more preferably from 7 to 30 degrees, and most preferably from 14 to 27
degrees. When the sliding angle is no higher than the upper limit of the
above-mentioned range, the suppression effect on substance elution during
the immersion exposure is enhanced. In contrast, when the sliding angle
is at least as large as the lower limit of the above-mentioned range, the
lithography properties become satisfactory.

[0369]The magnitude of the various angles described above (the dynamic
contact angles (advancing angle, receding angle, and sliding angle) and
the static contact angle) can be adjusted by adjusting the formulation
for the resist composition for immersion exposure, for example by varying
the type or amount of the component (C) and varying the type of the
component (A). For example, the larger the amount of the component (C),
the higher the hydrophobicity of the obtained resist composition, and
hence, the larger the advancing angle, the receding angle and the static
contact angle, and the smaller the sliding angle.

[0370]In this manner, the resist composition for immersion exposure
according to the present invention satisfactorily exhibits all the
properties required of a resist material for immersion exposure, and can
therefore be used very favorably as an immersion exposure composition.

[0371]Moreover, because the component (C) also includes a naphthalene
ring, the resist composition for immersion exposure according to the
present invention exhibits superior transparency to light having a
wavelength in the vicinity of 193 nm than compositions that include a
fluorine-containing compound having a benzene ring. Accordingly, the
resist composition for immersion exposure according to the present
invention is particularly suitable for immersion exposure that uses an
ArF excimer laser as the exposure source.

<<Method of Forming a Resist Pattern>>

[0372]The method of forming a resist pattern according to the present
invention includes: forming a resist film on a substrate using the resist
composition for immersion exposure according to the present invention,
subjecting the resist film to immersion exposure, and subjecting the
resist film to alkali developing to form a resist pattern.

[0373]A preferred example of the method of forming a resist pattern
according to the present invention is described below.

[0374]Firstly, a resist composition for immersion exposure according to
the present invention is applied onto a substrate using a spinner or the
like, and a prebake (post applied bake (FAB)) is conducted to form a
resist film.

[0375]The substrate is not specifically limited and a conventionally known
substrate can be used. For example, substrates for electronic components,
and such substrates having wiring patterns formed thereon can be
exemplified. Specific examples of the material of the substrate include
metals such as silicon wafer, copper, chromium, iron and aluminum; and
glass. Suitable materials for the wiring pattern include copper,
aluminum, nickel, and gold.

[0376]Further, as the substrate, any one of the above-exemplified
substrates provided with an inorganic and/or organic film on the surface
thereof may also be used. As the inorganic film, an inorganic
antireflection film (inorganic BARC) can be exemplified. As the organic
film, an organic antireflection film (organic BARC) and an organic film
such as a lower-layer organic film used in a multilayer resist method can
be exemplified.

[0377]Here, a "multilayer resist method" is method in which at least one
layer of an organic film (lower-layer organic film) and at least one
layer of a resist film (upper resist film) are provided on a substrate,
and a resist pattern formed on the upper resist film is used as a mask to
conduct patterning of the lower-layer organic film. This method is
considered as being capable of forming a pattern with a high aspect
ratio. More specifically, in the multilayer resist method, a desired
thickness can be ensured by the lower-layer organic film, and as a
result, the thickness of the resist film can be reduced, and an extremely
fine pattern with a high aspect ratio can be formed.

[0378]The multilayer resist method can be broadly classified into a method
in which a double-layer structure consisting of an upper-layer resist
film and a lower-layer organic film is formed (double-layer resist
method), and a method in which a multilayer structure having at least
three layers consisting of an upper-layer resist film, a lower-layer
organic film and at least one intermediate layer (a thin metal film or
the like) provided between the upper-layer resist film and the
lower-layer organic film is formed.

[0379]After formation of a resist film, an organic antireflection film may
be provided on the resist film, thereby forming a triple layer laminate
consisting of the substrate, the resist film and the antireflection film.
The antireflection film provided on top of the resist film is preferably
soluble in an alkali developing solution.

[0380]The steps up until this point can be conducted by using conventional
techniques. The operating conditions and the like are preferably selected
appropriately in accordance with the formulation and the characteristics
of the resist composition for immersion exposure being used.

[0381]Subsequently, the obtained resist film is subjected to selective
immersion exposure (Liquid Immersion Lithography) through a desired mask
pattern. At this time, the region between the resist film and the lens at
the lowermost point of the exposure apparatus is pre-filled with a
solvent (immersion medium) that has a larger refractive index than the
refractive index of air, and the exposure (immersion exposure) is
conducted in this state.

[0382]There are no particular limitations on the wavelength used for the
exposure, and an ArF excimer laser, KrF excimer laser or F2 laser or
the like can be used. The resist composition according to the present
invention is effective for KrF and ArF excimer lasers, and is
particularly effective for an ArF excimer laser.

[0383]The immersion medium preferably exhibits a refractive index larger
than the refractive index of air but smaller than the refractive index of
the resist film formed from the resist composition for immersion exposure
according to the present invention. The refractive index of the immersion
medium is not particularly limited as long at it satisfies the
above-mentioned requirements.

[0384]Examples of this immersion medium that exhibits a refractive index
that is larger than the refractive index of air but smaller than the
refractive index of the resist film include water, fluorine-based inert
liquids, silicon-based solvents and hydrocarbon-based solvents.

[0385]Specific examples of the fluorine-based inert liquids include
liquids containing a fluorine-based compound such as
C3HCl2F5, C4F9OCH3,
C4F9OC2H5 or C5H3F7 as the main
component, which have a boiling point within a range from 70 to
180° C. and preferably from 80 to 160° C. A fluorine-based
inert liquid having a boiling point within the above-mentioned range is
advantageous in that the removal of the immersion medium after the
exposure can be conducted by a simple method.

[0386]As a fluorine-based inert liquid, a perfluoroalkyl compound in which
all of the hydrogen atoms of the alkyl group are substituted with
fluorine atoms is particularly desirable. Examples of these
perfluoroalkyl compounds include perfluoroalkylether compounds and
perfluoroalkylamine compounds.

[0387]Specifically, one example of a suitable perfluoroalkylether compound
is perfluoro(2-butyl-tetrahydrofuran) (boiling point: 102° C.),
and an example of a suitable perfluoroalkylamine compound is
perfluorotributylamine (boiling point: 174° C.).

[0388]A resist composition for immersion exposure according to the present
invention is particularly resistant to any adverse effects caused by
water, and because the resulting lithography properties such as the
sensitivity and shape of the resist pattern profile are excellent, water
is preferably used as the immersion medium. Furthermore, water is also
preferred in terms of cost, safety, environmental friendliness, and
versatility.

[0389]Subsequently, following completion of the immersion exposure step,
post exposure baking (FEB) is conducted, and a developing treatment is
then performed using an alkali developing solution composed of an aqueous
alkali solution. Thereafter, a water rinse is preferably conducted with
pure water. This water rinse can be conducted by dripping or spraying
water onto the surface of the substrate while rotating the substrate, and
washes away the developing solution and those portions of the resist
composition for immersion exposure that have been dissolved by the
developing solution. By subsequently drying the resist, a resist pattern
is obtained in which the resist film (the coating of the resist
composition for immersion exposure) has been patterned into a shape
faithful to the mask pattern.

EXAMPLES

[0390]As follows is a more detailed description of the present invention
based on a series of examples, although the scope of the present
invention is in no way limited by these examples.

Synthesis Example 1

Step 1

[0391]8.00 g (37.7 mmol) of a [compound 1] represented by a structural
formula shown below was dissolved in 45.33 g of tetrahydrofuran (THF). To
this solution was added and dissolved 1.88 mmol of V-601 (a trade name)
(a radical polymerization initiator; dimethyl
2,2'-azobis(2-methylpropionate)) manufactured by Wako Pure Chemical
Industries, Ltd. The resulting solution was then subjected to a
polymerization reaction under a nitrogen atmosphere for 6 hours at
70° C. Following completion of the reaction, the reaction solution
was cooled to room temperature. Subsequently, an operation in which the
reaction solution was added dropwise to a large volume of methanol to
precipitate the polymer was repeated three times. The thus obtained
polymer was then dried under reduced pressure at room temperature,
yielding 4.25 g of a white powder (yield: 53%). This product is termed
"[polymeric compound 1]". This [polymeric compound 1] had a weight
average molecular weight, determined by GPC and referenced against
standard polystyrenes, of 13,500, and a dispersity of 1.37.

##STR00074##

Step 2

[0392]Subsequently, under a nitrogen atmosphere at 0° C., 10 g of a
THF solution containing 3.20 g (equivalent to 15 mmol) of the above
[polymeric compound 1] and 0.406 g (3.32 mmol) of dimethylaminopyridine
(DMAP) was prepared, and to this THF solution was added 3.20 g of
methanol. The reaction solution was returned to room temperature, and
then stirred for 15 hours under heating at 70° C. Subsequently,
the reaction solution was cooled to room temperature and extracted 3
times into ethyl acetate, and the resulting organic layer was then washed
twice with a 1N aqueous solution of hydrochloric acid and twice with
water. The solvent was then removed from the organic layer by evaporation
under reduced pressure, yielding 2.5 g of red crystals of a [polymeric
compound 2].

[0393]Analysis of this [polymeric compound 2] using 13C-NMR to
confirm the rate of deprotection of the acetyl groups revealed a
deprotection rate of 100%. This result confirmed that all of the acetyl
groups within the [polymeric compound 1] had dissociated.

##STR00075##

Step 3

[0394]Subsequently, under a nitrogen atmosphere at 0° C., 2.5 g
(equivalent to 15 mmol) of the [polymeric compound 2] was added to 50 ml
of a THF solution containing 4.3 g (34 mmol) of 3,3,3-trifluoropropionic
acid, 8.0 g (41 mmol) of ethyldimethylaminopropylcarbodiimide (EDCI)
hydrochloride and 0.2 g (2 mmol) of dimethylaminopyridine (DMAP), and the
resulting solution was then returned to room temperature and stirred for
3 hours. The reaction solution was then cooled to 0° C., and water
was added to halt the reaction. The resulting organic layer was washed
with water three times, and the solvent was then removed by evaporation
under reduced pressure. A re-precipitation operation was conducted by
adding an ethyl acetate solution of the thus obtained crude product
dropwise to heptane, thus yielding 2.9 g of the target [polymeric
compound 3] as a colorless solid (yield: 71%).

[0395]Analysis of this [polymeric compound 3] using 13C-NMR to
confirm the introduction of --CO--CH2--CF3 groups revealed an
introduction rate of 100%. This result confirmed that all of the --OH
groups within the [polymeric compound 2] had been converted to
--O--CO--CH2--CF3 groups.

[0396]Furthermore, the weight average molecular weight of the [polymeric
compound 3] measured by GPC was 17,500, and the dispersity was 1.37.

##STR00076##

Synthesis Example 2

[0397]Under a nitrogen atmosphere at 0° C., 2.5 g (15 mmol) of
4-vinyl-2-naphthol was added to 40 ml of a THF solution containing 4.3 g
(34 mmol) of 3,3,3-trifluoropropionic acid, 8.0 g (41 mmol) of
ethyldimethylaminopropylcarbodiimide hydrochloride (EDCl) and 0.2 g (2
mmol) of dimethylaminopyridine (DMAP), and the resulting solution was
then returned to room temperature and stirred for 3 hours. Following
confirmation by thin layer chromatography (TLC) that the raw materials
had been consumed, the reaction solution was cooled to 0° C., and
water was added to halt the reaction. Subsequently, the reaction solution
was extracted three times into ethyl acetate, and the resulting organic
layer was washed twice with water. The solvent was then removed by
evaporation under reduced pressure, and the resulting product was
purified by silica gel chromatography (eluent: heptane-ethyl acetate),
yielding 2.5 g of the target [compound 2] as an oily substance (yield:
60%).

[0402]The meanings of the abbreviations used in Table 1 are as shown
below.

[0403](A)-1: a copolymer represented by chemical formula (A)-1 shown
below. In the formula, the subscript numerals shown to the bottom right
of the parentheses ( ) indicate the percentage (mol %) of the respective
structural units within the copolymer.

[0409]Subsequently, the resist compositions of Example 1 and Comparative
Example 1 were each coated onto an 8-inch silicon wafer using a spinner,
subsequently subjected to a prebake treatment on a hotplate for 60
seconds at 100° C., and then dried, yielding a resist film with a
film thickness of 120 nm in each case.

[0410]A water droplet was dripped onto the surface of each resist film
(the resist film prior to exposure), and a DROP MASTER-700 apparatus (a
product name, manufactured by Kyowa Interface Science Co. Ltd.) was used
to measure the contact angle (the static contact angle) (contact angle
measurement: water 2 μl). The result of this measurement was recorded
as the "post-coating contact angle (°)".

[0411]Following measurement of the contact angle, the wafer was subjected
to a developing treatment for either 30 seconds or 60 seconds at
23° C. in a 2.38% by weight aqueous solution of
tetramethylammonium hydroxide (TMAH). The wafer was then rinsed with pure
water for 15 seconds. Subsequently, the contact angle was measured in the
same manner as that described above. The measured values were recorded as
"contact angle (°) after 30 s developing" and "contact angle
(°) after 60 s developing" respectively.

[0412]Further, the resist compositions of Examples 2 to 4 and Comparative
Example 2 were also evaluated in the same manner, although only the
"contact angle (°) after 60 s developing" was measured.

[0413]Furthermore, for Examples 1 to 4 and Comparative Examples 1 and 2,
the difference between the post-coating contact angle (°) and the
contact angle (°) after 60 s developing was determined, and this
difference was recorded as "Δ contact angle".

[0415]As is evident from the above results, the resist films formed using
the resist compositions of Examples 1 to 4 which included the [polymeric
compound 3] exhibited a higher contact angle prior to developing and a
lower contact angle following developing than the resist films formed
using the resist compositions of Comparative Examples 1 and 2 which did
not include a fluorine-containing compound.

[0416]These results show that the resist compositions of Examples 1 to 4
exhibited hydrophobic properties during immersion exposure, but then
developed hydrophilic properties during developing. These results
confirmed that the action of the alkali developing solution caused the
--CO--CH2--CF3 groups within the [polymeric compound 3] to
dissociate, thereby generating --OH groups and increasing the solubility
of the compound in the alkali developing solution.

[0417]An organic antireflection film composition (product name: ARC-29,
manufactured by Brewer Science Ltd.) was coated onto the surface of an
8-inch silicon wafer using a spinner, and the composition was then baked
and dried on a hotplate at 205° C. for 60 seconds, thereby forming
an organic antireflection film having a thickness of 77 nm. Each of the
resist compositions obtained in Examples 1 to 4 and Comparative Examples
1 and 2 was coated onto the surface of a substrate bearing the
antireflection film using a spinner, and was then prebaked (PAB) and
dried on a hotplate at 110° C. for 60 seconds, thereby forming a
resist film having a film thickness of 140 nm.

[0418]Subsequently, each of the resist films was selectively irradiated
through a mask pattern with an ArF excimer laser (193 nm), using an ArF
exposure apparatus NSR-S302A (a product name, manufactured by Nikon
Corporation, NA (numerical aperture)=0.60, 2/3 annular illumination). A
FEB treatment was then conducted at 110° C. for 60 seconds, and
the resist film was then subjected to a developing treatment for 30
seconds at 23° C. in a 2.38% by weight aqueous solution of
tetramethylammonium hydroxide (TMAH). Subsequently, the substrate was
rinsed with pure water for 30 seconds, and then spun dry, thereby
completing the formation of a 140 nm line and space (1:1) resist pattern
(hereafter referred to as a L/S pattern).

[0419]The above results confirmed that the present invention is useful as
a resist composition.

[0420]The present invention is able to provide a novel fluorine-containing
compound that is useful as an additive for a resist composition for
immersion exposure, a resist composition for immersion composure that
includes the fluorine-containing compound, and a method of forming a
resist pattern that uses the resist composition for immersion composure,
and the invention is therefore extremely useful industrially.